Personal Air Vehicles could be on the way and given that cities like LA are going to grind to a halt due to traffic congestion it could be pretty soon. Lots of companies working on designs. Some of the UFOs people have been seeing for the past decade or so could be LTA airships under development for passenger transportation. The park and ride scenario is what I think could work until the FAA gets off their a$$ and upgrades their ATC infrastructure (scheduled for 2025!?).
Once we get rid of all the cars what are we going to do with all that concrete? Could build houses on top of freeways I guess.
If you had a PAV what would you do first? Fly over your friends house and drop water balloons?