Yes, but many people also seem to think that cities are stuck in concrete.

Well, of course they ARE but you know what I mean... that they are
permanent. In reality, many domestic areas can be rezoned to include new density quite successfully in just 20 years.
Worldchanging: Bright Green: My Other Car is a Bright Green City
If we just REZONE a region with appropriate public transport and town planning provisions, with a long term goal of New Urbanism in mind, then natural attrition can take over. My main target is McMansion homes and suburban city design. McMansions only last about 50 to 60 years, are built from flimsy terrible materials, and are then pulled down. Instead of REBUILDING a mistake, why not prepare for the end of oil as the very optimistic article above suggests? Instead of energy efficient cars why not energy efficient (and trendier, longer lasting, and more economically viable) cities?