The EU is a fantastic historical example of how you cannot lead by consensus, and it shows us how it does just that by creating layers of overlapping bureaucracy that is redundant and emasculated from the get-go, only more expensive than that of the host nations respective departments. One of the few good things that have come out of that conglomerate is their policies on inter-nation immigration and work, as evident with the habits of polish workers during the recession versus Pakistani and N African immigrants, who are much more likely to be on the dole compared with the east Europeans who just returned home when the work went dry.
Our economy will be fine, even as the core of Canada shifts to the west. Quebec and Ontario has only themselves to blame. Otherwise, considering that the nation has done fine by sucking off of Alberta's teat for sometime, we should be alright. The US is in a rock-solid position because it is the world's reserve currency, and by that I mean the real currency for every failed state in the official sense (Zimbabwe) and the unofficial sense (IE NK Black Markets). Something big needs to happen for the US to get knocked off in the next twenty, and in that case all bets are off.
Where our real twilight may come in however has to do with simple demographics. As I've said before, the population distribution is becoming pretty skewed, to the eXtreme in Nippon and Ruskia. Russia only because the population is shrinking, and Japan because the women have just not been putting out for sometime, not that a large chunk of their younger men are really worth doing. Both nations are xenophobic at worst and ethnocentric at best, and do not share the same buffer that we do. If there's anyone who will fail first, look there.