2. Legality

For starters, for everyone to have a flying motorcycle in their garage, the mythical beast would have to be legal to fly. As far as the FAA is concerned, that means one of two things. The easiest and cheapest route for the manufacturer is to build what the FAA refers to as an ultralight vehicle---the FAA doesn't even use the term "aircraft" for them. Ultralights are largely unregulated. But there's a huge caveat. The max weight of a powered ultralight is 254 pounds. See section one, "Physics," to see the odds of hitting that weight. A Honda CB300, for reference, weighs around 350 pounds without wings or rotors and with just a tiny starting battery. Hitting 254 isn't impossible; at least one craft, the Jetson ONE, has done it. But because of the weight limitations, it can only fly for around 20 minutes before it becomes an anchor. The good part about the ultralight regs? One need not have any kind of license to fly an ultralight.