Would be fun, But would cost Trillions. It would make the roads useless eventually. Also how would you deal with Traffic and keeping people from crashing into one another. And if air traffic existed, people could fly into buildings, crash into pedestrians and police chases would be havoc. Its possible yes, but is it really worth it :p
Also it would be no fun if you were kept within a radius or Invisible road, that would be just a copy of roads but in the air. Although would make more space on the ground, providing people stopped driving. Only the rich would be able to afford the assets to actually use flying cars (Electric, Jet fuel, Vehicle cost etc).
I would have it so there a system on the flying cars which stops you fro crashing into buildings, other cars and a boundary between the ground. For example the flying cars can only fly above 1000m but no more than 5000m. This would prevent the cars flying into ground objects, and planes way above.Then there could be stations located in the sky that bring the cars down to the ground.
The concept is amazing, but the execution will be difficult.
