The fortunate and successful New Urbanists will be the ones who can find local infill projects in small towns and small cities associated with farming, water transport, (perhaps rail too) and water power. I do not believe personally that we will retrofit much of suburbia in the way many people wish we might. The capital won't be there, and I'm rather convinced that the population is headed down - though this will be a lagging effect, because even starving people have sex.