The 28 countries (soon to be 27) of the EU vary considerably in their economics, religion (or lack of), languages and national characters. Originally the creation of the EU was midwifed by the US after WWII, driven by a need to ensure both a “western” democratic, peaceful Europe, and common bulwark against the Soviet Union that their desire to create their own strategic depth. Following the fall of the Soviet Union, the EU grew to include former Easter European countries and consolidated membership on the Med with the inclusion of Greece. Overlaying everything was the introduction of the Euro in 2000; the common currency that now exposes the fundamental economic fragility of the entire European experiment. Meanwhile other pressures expose the centre's determination to impose their culture and cultural priorities on member nations.
All this bares a more than passing resemblance to Yugoslavia, formed out of the ashes of WWI, with Balkan enemies forced into a single national entity and economy with a faux common history, common currency and a similarly non-democratic central government. Yugoslavia was then reformed into a single country after WWII. Unfortunately, Yugoslavia was held together not by a common democratic system with open and free elections, but by a single party that exercised coercive control over a number of national groups, with central control in the hands of one national-ethnic group, the Serbians.
Equally unfortunately, the EU is being held together by a non-democratic system dominated by a single national / ethnic group that exercises coercive power over the economic and political activity of member nations. Perhaps the major difference, other than sheer size, between the two is leadership of Europe by a finance-dominated technocracy instead of a political party.
Further, the pressures of Brexit may well contribute to individual countries attempting to negotiate with the UK to cement their own best interests, to the detriment of the rest of the EU. President Macron of France has this week warned that such individual dealing may result in a “prisoners’ dilemma” problem, potentially splitting the EU. 
We must hope that when the inevitable breakup happens, what follows is a Slovenian divorce trajectory and not the Bosnian. The only realistic alternative will be a civil war of consolidation of European power in the hands of a single dominating ethnic group, with the potential for a result more similar to Syrian history of aligned ethic, clan and tribal groups under a dominant ethnic - tribal group. That didn't work out too well when exposed to external interference after the "Arab Spring".
That, after all, is what happened twice in the past century, resulting the 50 – 100 million deaths in those “World Wars”. 
So our resulting options are Slovenian or Bosnian in nature; individual national independence with the acceptance of the centre, or a bloody civil war designed to change the “reality” on the ground through the imposition of ethnic and cultural domination.
We’ve been down this road already, twice. I hope Europe and its constituent parts will take that former. My fervent hope is that the EU will find a way through. My fear is it might not.
2. Forced Friends
After two twentieth century wars for central European domination, Germany and surrounding nations lay in waste. As the perpetrator of the wars, the Morgenthau Plan of 1944 was to create an agrarian Germany that would never again have the industrial might to create and field an army strong enough to dominate Europe. Roosevelt himself wrote "Too many people here and in England hold the view that the German people as a whole are not responsible for what has taken place – that only a few Nazis are responsible. That unfortunately is not based on fact. The German people must have it driven home to them that the whole nation has been engaged in a lawless conspiracy against the decencies of modern civilization."
This plan was never going to survive the realities of post-war Europe, and the need initially to feed and rebuild, and ultimately to face down the Soviet Union. And in Western Europe there was only one industrial power. As Yannis Varoufakis points out in his book "And the Weak Suffer What They Must?", even at the end of the Second World War in April 1945, defeated Germany still had over double the factory capacity of France.
And so while Germany was forgiven for the war (including 70% of its debt) in order to become the industrial bulwark against communism, the rest of Europe was required to play along, pretending that is was just a few strange creatures called “Nazis” that perpetrated war and destruction across Western and Eastern Europe, deep into European Asia and across the Mediterranean. France was none too pleased, as the initial stages of what became the EU started specifically in order to enable Germany to rebuild its industrial base while (hopefully) limiting the ability or need for Germany to convert that industrial based into a war machine, again. France and the Benelux (Belgium, Netherlands, and Luxembourg) countries had little option but to attempt to contain Germany, just as the Americans used Germany to help contain the USSR. German containment took the form of NATO and the economic links that lead to a strong Deutsche Mark and eventually to a strong Euro. Yet the source of the strong Deutsche Mark was the economic disparity between Germany and the rest of Europe, a disparity that exists today.
Fundamentally then, the EU began as an economic union in which former adversaries were cajoled into merging interest to the ultimate benefit of all (or so the theory) with the immediate and lasting greater benefit to one - Germany. Friends they pretend to be, but memories are still there on one side, and while forgiveness may be official, forgetfulness and re-framing is the rule. Crimes against occupied countries and peoples were committed by "Nazis" not by Germans. To this day it is almost impossible to find a German whose father or grandfather was a Nazi, or who committed war crimes. In the formerly occupied countries, people today remember growing up sitting on their grandmother's lap, hearing tales of the occupation.
These memories do not disappear when those that went through the occupation die, these are the memories that forever undermine the politically and socially appropriate forgetfulness required for countries and peoples to work together.
The treatment of Greece by the German Finance Ministry and the ECB (not to mention the IMF, etc) has done little to encourage forgetfulness or forgiveness. The forgiveness of German debt after multiple aggressions still burns Greece, as German (and to be fair, French and other) major banks and national institutions gouge the pitiful remaining Euros out of Greece to protect their non-Greek shareholders and governments.
While Greece is probably the most visible example of how the EU is failing Europeans, there are other examples across the continent. These range from economc disadvantage, cultural suppression, loss of legal sovereignty, and the imposition of demographic choices opposed by the individual member countries.
3. Yugoslav breakup
It is important to remember that Yugoslavia was a multi-ethic "republic" and an economic union, forged out of the First and then again out of the Second World Wars. So in many ways Yugoslavia provides a model of the EU, including multi-generational cultural integration and an enforced political as well as economic union. Yugoslavia was also an economically successful country, certainly when compared to the rest of the Warsaw Pact and other Socialist countries.
So why did Yugoslavia fail?
While there were a number of contributory causes, the death of Josip Broz Tito in 1980 began a long process of dis-union and resurgence of nationalism, driven in no small part by each of the constituent national groups losing faith in a centre dominated by one of the nationalities; the Serbians. With its capital in Belgrade, it was always natural that Serbia would be the dominant nationality.
Yet Yugoslavia had come through a period of significant market liberalisation and economic growth, and had, in large part, achieved reasonable and consistent GDP growth through increase international trade. Unfortunately that liberalisation stagnated due in part to internal demands of additional democracy in Croatia.
In his paper "Socialist Growth Revisited: Insights from Yugoslavia", Leonard Kukić demonstrates that Yugoslavia was able to demonstrate considerable economic growth through the 1960s and 1970, but were unable to continue that growth into the 1980s.
"Given their capacity to embark on radical reforms during the early years, how come Yugoslavs were unable to reform their economy later on? Policy makers were aware of remedies, but politics got into way. Duˇsan Bilandˇzi´, a historian and a politician, reports in his memoirs that in 1970 the Central Committee of the CPY accepted draft proposals aimed at liberalising capital markets and entry of firms (Bilandˇzi´c, 2006). The aim of these policies was to diminish or eliminate the apparent labour distortions. However, these policies were abandoned with the flaring of political and ethnic tensions by the 1971 calls for democracy in Croatia, a member republic of Yugoslavia.
The inability of Yugoslavia to cope with the 1979 oil shock was compounded by a major domestic shock. The lifelong president of Yugoslavia, Tito, died in 1980. He was replaced by an ineffectual collective presidency containing nine members. They lacked political capital to pursue planned reforms."
The breakup of Yugoslavia and the following civil war is frequently "blamed" on the Serbians and their attempts to create an ethnically cleansed territory that included major portions of Bosnia. Ultimately Slobodan Milosevic was convicted of war crimes in The Hague, and died in prison. Numerous other Serbians have been tried and convicted, as have Croatians and others.
It is also worth remembering that there was a history of inter-communal violence on a massive scale during WWII in particular, with the Croatians Ustaše responsible for the deaths of hundreds of thousands, and had the goal of an ethnically pure Croatia. While we (now) think of the Serbians and the primary culprits, they look to a long history of being the underdog, fighting to protect their culture and society.
So the lack of strong central government, faltering economic performance, long memories, rejection of a centrally imposed mono-culture, and rising nationalism worked together to doom Yugoslavia.
4. Next for Europe
Probably the single largest difference between Yugoslavia and the EU today is the lack of large scale inflows of economic migrants (politically correctly labelled "refugees") from Africa and war-torn Middle-Eastern countries. This influx, aided and abetted by EU member countries public comments and demonstrations of welcome or at least acceptance on arrive, has created a new dynamic not present in Yugoslavia prior to its breakup; an imposed external cultural disruption seemingly imposed by the central government, in this case the EU with its mandatory quotas imposed on member countries.
The issue is not immigrants, as the Open Boarders policy has facilitated the flow of Europeans between countries for almost two decades. The issue is the forfeiture of national sovereignty, with the illegal immigration issue providing the highly visible demonstration of such forfeiture. It has been too easy to label Europeans as racist for opposing illegal migration, yet to do so sweeps under the carpet the far wider range of issues that are associated with centralised determination of individual cultures, nation-level priorities, and the ability of the dominant participants to override the desires of local peoples and communities.
Below are a few of the strains facing Europe in the form of specific country tensions with the EU. These are not the only tensions, and while none of these may be the spark, quite possibly one of them could.
5. The Precarious State of the EU: Other pressures
The United Kingdom is by far not the only European country or region that is experiencing problems in the relationship with Brussels. The European experiment continues, and at its heart remains a struggle between demands for regional and national sovereignty, and the desire for a continued concentration of power in the centre. How this will end remains an open question, the experience of the UK is only one example of the stresses that Brussels is experiencing, some of which challenge the current nation-states that make up Europe, while others challenge the very concept of a single unified Europe.
The following are five (only) specific examples of the ongoing stresses on the European Experiment. These will not go away quickly, and some threaten the very cohesion and assumption of an "Ever Greater Union" as demanded by Brussels and the European Commission. There are a number of other examples of stresses, and we will watch these evolve over the coming months and years.
On October 27th, the Catalonia Parliament declared independence. This was foreshadowed by the family of the Catalan president (Carles Puigdemont) leaving the country the day before. How Europe and the EU respond over the coming weeks and months will impact the viability and future of the EU and the European Commission. It is no surprise that the UK has rejected any suggestion that it should recognise Catalonia, for to do so would undermine any hope of a successful Brexit negotiation.
After arrests and (gentle) suppression, new elections were held in December 2017. Voter turnout was high, at around 80% of eligible voters, and the pro-independence parties won.
The mess in Catalonia will not be getting better any time soon, and it was the Spanish Government's fear of contagion that resulted in the strong and immediate rejection of any Scottish dreams of joining the EU as a separate country. That contagion appears to have come to fruition, after decades of perceived grievances by both sides, and a not-fully forgotten legacy of the Franco era.
With the referendum, Article 155 of the Spanish government, and now a renewed electoral mandate for independence, we can only watch and hope that this does not become the European Union's first fully fledged civil war. Regardless of the outcome, this cannot and will not remain a Spanish problem.
The recent elections in Austria should not come as a shock, as there has been a growing backlash against centralised Brussels control and usurpation of national priorities, with the immigration crisis providing the catalyst for demands for greater local authority. Yet the Austrian People's Party, the conservative party founded in 1945, instead of running in second place, finds itself with the highest percentage of the vote and number of seats, and with the ability to go into coalition with the right wing party, the Freedom Party of Austria.
"Austria became the latest European country to take a sharp turn right on Sunday, with the conservative People's Party riding a hard-line position on immigration to victory in national elections and likely to form a government with a nationalist party that has long advocated for an even tougher stance."
"If there's one topic that really dominated the campaign, its migration and integration," said Sylvia Kritzinger, a political analyst at the University of Vienna. "Especially with Kurz, it always came back to immigration. We had very little discussion of the issues beyond that."
For most of the past two years, these two conservative parties have polled at a combined greater than 50% support, and the snap election called this year has created the opportunity for these two to rule without the need for centrist or left-of-centre support.
Should the new government in Vienna actually follow through on their platform, they will quickly find themselves in the same situation as Poland, potentially having their voting rights restricted, or more.
Poland is not alone in its desire for full EU membership on its own terms, and recent Polish law has been in direct conflict with EU legislation and regulation. Poland's primary objective in joining the EU was freedom of movement and economic advantage, with an ultimate joining of the Eurozone. Security from Russian hegemony was achieved, they hope, by joining NATO. This was designed to balance against the need for, and to reinforce, the concept of collective defence.
Yet Poland is a profoundly conservative and Roman Catholic country now joined to a sectarian Europe. Recent Polish law has been in conflict with the EU to the point that Brussels has discussed sanctions against Poland. While there is no realistic chance that Poland would exit the EU, it may contribute to a paralysed Brussels unable the marshal the 27 votes required for almost anything.
As recently as August 2017, there were threats that Poland could lose its voting rights in Brussels. Such a move would not engender much support from other marginalised EU members.
"The fact that a European tribunal decision is rejected so arrogantly is evidence of something very dangerous in my opinion — it is an overt attempt to put Poland in conflict with the European Union," Tusk said. (EU President and former Polish Prime Minster)
Tusk noted that several actions of the Polish government appear to be "very controversial" and could risk the country's continued EU status. Brussels has already been considering triggering Article 7 of the EU treaty, a legal process which could suspend the country's voting rights.
"It smells like an introduction to an announcement that Poland does not need the European Union and that Poland is not needed for the EU," Tusk noted.
The two primary cultural groups in Belgium have a long history of working together, primarily because the country was created as an artificial buffer state between Germany and France in 1830. Roman Catholic Flanders and Roman Catholic Wallonia historically had less to fear from each other than from their Protestant or Anti-clerical peoples of the Netherlands and France. The second half of the 20th Century and the creation of the EEC reduced those external threats, and created the conditions for sectarian conflict. While Belgium is not going to collapse into civil war, it has been referred to as the "First Bosnia". 
In 2010 Belgium managed to go for 541 days without a government, and the two regions continue to co-exist, but with continued moves to greater regional autonomy. This was after the 196 days without a government in 2007.  (https://en.wikipedia.org/wiki/2007%E2%80%9311_Belgian_political_crisis)
With Flanders contributing close to 80% of GDP while accounting for 65% of the population, a breakaway, or even a devolution that strips Wallonia of tax revenues, will force Brussels (EU, not Belgium) to face the prospect of a further long period of no-government in Belgium, or potentially a desire for full independence by Flanders.
5.5. Czech Republic
And so, with 61% voter turnout, the Euro-sceptic oligarch Andrej Babis is to be the new Prime Minister of the Czech Republic. The October 20 election puts Mr Babis in line to form a new government.
"The 63-year-old made his estimated $4bn (£3bn) fortune in chemicals, food and media - but he has also faced numerous scandals including a fraud indictment and accusations he was a communist-era police agent. He says he would not bring the Czech Republic in to the Eurozone but he wants the country to stay in the EU, telling Reuters he would propose changes to the European Council on issues like food quality and a 'solution to migration'."
This represents a core EU member states that has turned from the even-closer union demanded of Brussels, making the "every closer union" appear to be more for a French, German, Dutch, and Belgian dream than an actual potential outcome for the foreseeable future.
6. Slovenia or Bosnia?
With the stresses in Europe, and that disparity that has been caused by a semi-centralised union devoid of effective internal transfers, and therefore with countries unable to create balance through exchange rate management or regulatory discretion, pressures continue to build, ultimately to a breaking point.
If Germany, and to a lesser degree France also, radically changes their outlook and policies to be “Europe-first, then Germany” instead of “Deutschland über alles” then there is hope. The changes required would be at the political, economic and cultural level and would be so far reaching as to ensure the swift demise of any government that attempt to implement the needed changes. Therefore I hold out little hope that German will enable the changes needed to keep Europe together.
So our resulting options are Slovenian or Bosnian in nature; independence with the acceptance of the centre, or a bloody civil war designed to change the “reality” on the ground through the imposition of ethnic or cultural domination.
We’ve been down this road already, twice. I hope Europe and its constituent parts will take that former.