What will our cities be in 25 years? The question calls up a caricature, a grotesque vision of ultimate ghettoization. The vision involves a permanent underclass of poor people, largely defined by race, in rotting urban enclaves with no public transportation worthy of the name. An affluent class lives far off in automobile suburbs, probably gated. A skyscrapered business center rises like a sterile Acropolis. Government is off in what it calls a "campus" somewhere. And all of it is spread out at regional scale, consuming enormous quantities of landscape, more like a small nation t