Well, we may find out someday...or we may not.

Looking at the situation around here (small town and rural), I think people would pull together, mostly help one another, and rapidly form community associations to get things reasonably in order....but things would not be good at all in the larger urban centres, because there is little or no sense of community there. There would be rioting, violence, gang warfare, and bloodshed in those places. A lot of refugees would start fleeing to the rural parts, and the rural people would have to deal with it somehow.

Eventually it would sort itself out one way or another, but a lot of people would suffer before it did.