I've only seen the first few minutes of Ellen Dunham-Jones' Ted Talk Retrofitting Suburbia, so I can't comment on it too much. My first reaction to the concept of trying to urbanize suburban settings is that the result would be pretty compromised. The idea is to make existing suburbs into more complete communities instead of separate working and living zones. I fear though, is that it is really hard to reclaim land set aside for cars. I would guess that it's nearly impossible to reduce the number of car lanes on most roads to put in sidewalks and a bike path.
One of the saving graces, it seems, might be that suburban office parks and retail areas are notoriously inefficient users of space. The roads may be set in stone, so to speak, but when one of these facilities gets repurposed, there is lots of space for adding walking paths, green spaces, and run-off management features.
Right now, I need to get back to work, but I plan to watch the full talk next chance I get.