A unified European state will be reality within our lifetimes. I'd be willing to put a significant amount of money on that.
At this point, I don't think its purely structural incentives driving the EU train anymore. That may have been the case during the Cold War or during the 90's, But now, I think that you have a new national identity emerging on the European continent -- a European Identity -- and that identity is, like all national identities, seeking its own state.
Slowly, like a prion, the European identity will infect mind after mind, and the opposition will begin to drop away. Countries will give up more and more sovereignty to Brussels, and the United States will have a peer competitor on its hands.
I'm not convinced that this process can be blocked at this point. We need to start preparing for a European superstate now.