busyInterestingly, all of them are playing out -- in different places at different times. Some countries are shifting rather gracefully. Some are staggering. Quite a few have already fallen apart or are in the process of doing so. It's less about politics or religion and more about resources, or lack thereof. There are actually major postapocalyptic markers such as armed raider caravans and oil/gasoline thieves.
Regarding America's problems of suburban sprawl subsized with Ponzi economics, the more things fall apart, the more people will leave in search of somewhere less wretches. Since a large portion of suburbs, cored-out cities, and planned-obsolete buildings will fail at more or less the same time, there will be a lot of people wanting to go somewhere else also at the same time.
There are several possible approaches to this:
* Build from strength. Any town with a pre-car-central downtown can work to revitalize that. Any suburb with a spot of retail and/or apartments can aim to densify around that. You can't save everything, but you can save the most workable parts.
* The small towns that are disdained now will become much more valued later, if they survive long enough to get there. Most have a pre-car downtown surrounded by some modest houses in a grid pattern, and those modest houses have yards to grow a garden. That's viable. So it's likely to attract people away from the coasts and the big cities back to the heartland and smaller towns. Especially with climate change making coasts and cities riskier places to live. So here's a tip: if you want cheap, walkable living space then don't look where everyone else is looking. Check somewhere else, because a lot of it is standing empty, begging for occupants.
* Start from scratch. This is the one few people are talking about, but it's what happens any time a civilization collapses. People just walk away and shack up wherever they think they can build without getting raided. This has the supreme advantage of avoiding the massive wad of debt and solution-quashing regulations that modern cities have become. If you build in the middle of nowhere, you are free to build what you can afford and maintain, not what some ignoramus says you have to build. Go it alone and you maximize freedom, but team up with like-minded people and together you can afford more than any individual could. The main downside to starting from scratch is that you'll have to get by with a lot less frills, but if you can't afford frills or the city has fallen apart past offering them anyhow, you're going to come out ahead by leaving.
Trailer parks are commonly built similar to this on the edge of town, just past the zoning map that would quash them further in, or even in the middle of nowhere. If you're lucky enough to have a town that allows them inside the zoning map, you can use this approach to create fairly dense, walkable neighborhoods that still offer freestanding homes and a patch of grass. It's straightforward to make a trailer court into a decent neighborhood with a bit of workspace. Just remember you need storm shelters.