I agree with otterpop: the US won't be swayed to give up their cars in the near future. I also appreciate boilerplater's summary of Kunstler's book. I haven't gotten around to that one yet!
But IMO, the U.S. has created to much sprawl to simply forget about it. We are in a unique (as far as I can tell) situation of an overwhelming amount of suburban sprawl, and even as we implement better methods of building and transportation, the car will still be a necessity in many communities.
I am a huge fan of sustainable growth and all it has to offer--I'd rather ensure the preservation of some kick-butt natural areas in my country than let everyone build their own villa--but that's another story. In the case of the US, however, I think sprawl has pretty much won :/ like it or not. Sustainable development in the future will hopefully be able to mask the areas currently riddled with sprawl, but they'll still be there.