I mean that literally, by the way: some time in the next twenty years we’re going to see the inhabitants of Detroit simply give up and move en masse in a folk-migration; the city will become unincorporated; and then the forces of Nature will swarm in and quickly reduce the whole place to a set of ruins that will make the career of some lucky Fortieth Century archeologist when he or she stumbles across the proof that the mythical Mo-town of First American Republic legend actually existed. With any luck, the Robocop statue will likewise survive and make ’em think that this was the Mo-towner’s titular god.
PS: Yeah, well, I’m pretty sure that the city fathers of Cahokia weren’t really planning to ever move, either. Or Ctesiphon. Or, heck, you can look up “Lost Cities” on Wikipedia as easily as I can. The point is that cities can die. Even American ones.