[What I see as more likely is that the UK invokes Article 50, goes through a financial crisis, and then the EU offer to cancel our Article 50 invocation and let us stay in the EU if we join the Euro and Schengen.]
I think if one more country votes to leave between now and then a renegotiation and some core constitutional changes become more likely.
The basic problem is that the Leave side lied about the benefits of leaving, but they were absolutely correct that the core of the EU has become a neoliberal financial dictatorship with rather thin democratic wrapping.
If bigger cracks start appearing in the structure the leadership is going to have a choice between accepting more real democracy, or having the whole thing come crashing down.
Currently there are no bigger cracks visible, but the economic foundations in most of the EU are very shaky - so who knows where we'll be a couple of years from now?
Why?
If it is positive, thing that it is highly dubious
Two years! Pretty sure it will be around. Now if you'd said, say, 20 years then you might have a point.
Personally I very much hope the EU is around in 20 years, but massively reformed. I think it needs far more transparency and clarity (no more "<insert random city here> Agreement"). Also every policy which doesn't have a good reason to be decided centrally should be delegated down to local level, even to sub-national / city / county level.
And you're right about the shaky financial foundations. I think the Eurozone, assuming it doesn't collapse, should be a separate organization entirely.
They aren't going to join neither
Also this is certain to make people even more pissed
Schengen does not make sense for the UK. (They have their own deal with Ireland because of Northern Ireland called the Common Travel Area which might go down the drain as well)
If that would kill the EU then the EU probably deserves to die. Otherwise it suggests that it only persists through the inability of its consituent populations to challenge the status quo.