I agree with David.

Also worth noting is that wars have started over less, and many of those have been in Europe.

When sovereign states are cobbled together with paper, it better be some damn good paper, as even a single flaw can be fatal.

The US Constitution was the paper that cobbled together 13 sovereign states; but it pointedly both ignored and avoided one, unsolvable issue....and it damn near destroyed us. We had enough commonality of language and culture to battle back from the brink, I don't believe that exists in Europe. EU may have been too bold; a move that vaulted Governance too far in advance of where populaces stand on the matter of sovereignty and what they are willing to surrender to government. (see the slide I posted on the defining COIN thread)

To ignore the people and to instead seek to preserve the EU as it stands may be folly. Perhaps, like the NCAA there needs to be some new conferences drawn up to create more effective aliances...but that too can create competing teams of states and also lead to war.

All paths can lead to war or peace (and typically do). I doubt it will be a "small" one though when it pops, and I hope, that like in the last two, the US does not have a large standing army when it happens and is thereby forced to sit out the first couple years once again. Far better to be in a power position at the finish, than at the start.