"The resulting cities may need to look and feel very different - different, perhaps, from the common understanding of what a modern American city is. Rather than trying to lure back residents or entice businesses to build on vacant lots, cities may be better off finding totally new uses for land: large-scale urban farms, or wind turbines or geothermal wells, or letting large patches revert to nature. Instead of merely tolerating the artist communities that often spring up in marginal neighborhoods, cities might actively encourage them to colonize and reshape whole swaths of the urban landscape. Or they might consider selling off portions to private companies to manage.
A few of these ideas are actually starting to be tried."
Cleveland, Detroit, and Lackawanna, New York are all discussed.