I think we'll see a migration back into the cities coupled with improvements to public transportation and urban biking.
I've already noticed fewer large SUVs on the road, and many more "crossovers" (i.e. minivans that look like SUVs), so people are trying to save gas where they can.
The biggest complaints among my friends when it comes to biking:
1. How to transport 1-3 year-olds and the required gear (diapers, toys, food, etc.)
2. Too dangerous to go on busy roads (suburbs mean minimum 35mph speed limit and lots of distracted soccer moms)
3. Live too far from work (>20 miles, so it would take much longer than driving)