> national identity will fall by the wayside as they come to the crushing realization that national identity doesn't put food on the table or keep the lights on
You know, every other nation in Europe has a period in history when they were persecuted and being deliberately destroyed, both physically and psychologically. Sometimes for hundreds of years. We've got "killing fields" and battlefields everywhere - please, do take into an account a legacy of more than 2000 years of non-stop, all-out wars - and more than one such a field was created specifically for people of one nationality. On the other hand, almost every single nation in Europe has a (mostly real! but sometimes imagined) "golden age" in their history they can cling to; a period where that nation was (possibly a part of) a global superpower.
Given that, I don't believe nationalism is going to die just because people are getting hungry. I mean, lots and lots of death, torture, persecution, as well as preaching, propaganda, and education didn't kill nationalism - why do you think lack of money would? Some European nations are practically built upon martyrdom and, if anything, it made European nationalism even harder to leave behind, change or even soften a little.
> Europe will start to look more like Canada and the US
I'm repeating myself here, but discarding more than 2k years of history is dangerous when making predictions about the future. Europe already was a melting pot of cultures for a while, back when nation-states were not fashionable yet. A few times, at that, in different ages. Never once did this make Europe a peaceful continent or made nationalism disappear.
US and Canada are unique in that, historically, it's a bunch of people getting together and promising to leave the past behind. That, of course, doesn't take into account American natives, but whatever: that's NOT happening in Europe. You'd have to demolish most of the cities to destroy thousands of buildings and sculptures still, remainding Europeans about just how heinous their neighbour is or just how just was their neighbours massacre. And that's the easiest part, because then you'd have to destroy and eradicate a good part of culture and art. And then, after a couple of generations under heavy propaganda, maybe you'd have a place roughly comparable with US.