Shrink your city
What to do with a deteriorating city? As the New York Times reports, you can speed its decline, and selectively demolish and reconcentrate inhabitants to smaller, denser neighborhoods with reformed centers, and return outlying lands to pasture and forest. Not a bad idea, and the good news is, Flint, Michigan is going to try and do this without the use of imminent domain. Rome grew and shrank, and maybe we can all learn a lesson and get creative with the design and reorganization of our cities as times force us to economize.
Instead of demolishing, why not leave the buildings to ruin? We could speed up the process by cutting holes in the walls Matta-Clark style if need be. Entire ghost towns of McMansions and tract homes could be left to rot as a reminder of outmoded planning. How goth would that be?