...as we know it.
Brexit, I reckon, will be the straw that breaks the EU's camel's back.
As we saw with Indyref1 and the referendum once people have to put their cards on the table and make their hands count i.e. polarize the situation, vote and affect the reality on the ground, then divisions and the like take place for real, and in some cases breakups. Whilst there are no real consequences, only debate and speculation, these tensions are endured and held in check in the background. Only when they come into the full light of day of being implemented do the sparks start to fly.
Well, with Brexit this type of situation will be forced onto many of the EU institutions to put their cards on the table about how to deal with the UK. Each having their own agendas and ideas about what is good for them and then having a vote on the deal. The EU is already in crisis with the Euro (youth unemployment etc.), immigration (Turkey), Trump's coolness towards the EU and the NATO issue he has raised, and their Eastern front with Russia where the East Europeans experiences of the Soviet Union have made them edgy and in need of our security and military know how. The general discontent of the EU in some quarters (the weakening of the political arena) and differing views about where the EU should progress to, or pull back to previous positions etc.
All this, not including Brexit, is causing riffs in Brussels and the EU to start to crack up. Those at the top know it. Though they see Brexit as being lower down on their list of importance and matters to focus on, it is in fact something that is going to pull them all together and make them see, in stark clarity, just how fractious the whole of the EU is and how their various opinions and ideas are pulling away from each other.
Tusk has said he wants the exit fee (60-50 billion) to be settled first before trade talks begin. That's because the EU is short of funds and our exit will make matters worse so they want to fix this unrealistic high sum before anything else. He also talks about the EU working as a united group in Brexit but this just to highlight the fact that this exactly what they are not.
Brexit will split them into many fragments and will precipitate the eventual breakup of the EU. It is unlikely, in my view, that we will even reach the end of the Brexit negotiations, but they will fizzle out and morph into some holding arrangement with the deflated EU state that could linger for years.