If there were as many private helicopters and planes as there are cars, helicopters and planes would not be safe anymore. Even with fancy antigravity technology. You simply can't have flying things in city streets. If things go wrong, you have cars crashing into the 50th floor of a building, or dropping straight on the ground on people from 200 meters.
The FAA will obviously have to regulate such technology and autopilot tech would obviously have to guide any such devices for the most part. Commercial airplanes can take off and land today without the aide of the pilot In fact they believe the Korean Airlines accident that occured a few months back at SF International airport was because the pilot turned off the auto navigation.
It's worth noting that the FAA estimates there will be 30,000 + private drones whizzing over our heads at any given time by 2020 which is just 6 years from now.
The thought of having modern city street traffic in the sky is still just insane. It will not work. Full
autopilot navigation in city street traffic will not even work for cars on the ground.
30,000 drones over the whole US? How about 30,000 drones just over downtown Manhattan? On a Sunday.