Like gerv said, I think we've already been seeing it on a smaller scale here in the U.S. The latest bike boom has been driven a lot by people who want to use bicycles for transportation/commuting/errands, because gas prices and the cost of maintaining, driving, and parking a car in this day and age is simply too high for very short distances. I can see more people opting to walk or take a bike ride when the distance is around 1-5 miles one-way.

I can see more and more people turning to this in the future as gas prices continue to rise, but I don't see too many of them choosing to go 100% car-free unless they live close enough (or with good public transportation) to everything and everywhere they need/want to go (stores/jobs/parks/etc.).