There would need to be a lot of changes to the traffic system before flying cars ever happened. I’m not sure if it would even be a logical step forward in technology. It’s definitely possible though: http://www.youtube.com/watch?v=Xo0MEQSGW8w
Depends on what you mean by a flying car? Is a small plane or a helicopter not a flying car? It would be really interesting if everyone could own and run their own flying cars, but it would be hard to figure out how roads and traffic would work. Plus it would probably be worse if you crashed, because as well as going fast, you’d also be falling too.
I think the next big step with cars will be lots of automatic stuff. We already have cars that can park themselves and cars that can drive themselves on predefined tracks, so maybe we’ll get cars that can drive us from home to work using things like GPS and traffic monitoring. I don’t know how to drive, so this would be great for me!
The main problem I think would be the propulsion system. If we could get something that generated the force required to get the cars up in the air without requiring too much energy then they would be feasible. Flying cars are possible with todays technology I would think but wholly impractical.