Flying cars will never be probable do to the fact there is no way to make sure everyone has a license and the FAA would not be able to regulate the amount of flying crafts in the air to make sure nothing happens.
Also, there is no way to cover a mainstream amount of aircrafts with insurance because if there is a crash the debris will also do damage because it will most likely be used over peoples property.
Nevertheless if there were few amounts of flying cars that were used for emergency vehicles and police then they will work fine, but as for commercial use flying cars will never be used as the main way as transportation.