Most of these are probably going to have to be autonomous. It's the only way to make this safe. They might introduce a special license allowing you to fly them manually after you take a course, but this will probably only be allowed in very sparsely inhabited areas and may be more of a tourist gimmick than anything else.

For practical everyday use you will have to have these run on automated systems that keep track of where others are at any given time and can fly along designated virtual lanes. I am not expecting these to be individually owned, at least not at first, but rather have taxi services owning an entire fleet of them and you just call them via an app.

The main problem right now is not the technology it's how you regulate them to make them safe, and i trust that China has a good handle on that, and if i had to guess i'd say they'll probably finish implementing the regulatory legal structure for this to become commercially viable in a couple of years, with possible setbacks if there is any kind of serious accident in the meantime.

A few crashes is all it will take for these to immediately be heavily regulated, assuming they won't already be heavily regulated right out of the gate.

This is basically what i think too. The main obstacle now is getting the legal framework in place to regulate this new mode of transportation. No other country has done it yet so this is uncharted territory, but if any country can figure it out it's China.

It is mathematically impossible for flying (or rather hovering, to be more precise) vehicles to be more fuel efficient than ground vehicles.

I mean think about it from a physics standpoint. A flying vehicle needs to constantly expend energy to overcome the force of gravity pushing it down. A ground vehicle only needs to overcome friction forces, the main one at slower speeds being friction between the ground and wheels. It's the same reason why pushing a cart to carry heavy loads is easier than carrying something by just lifting it in your arms. It's why wheels were invented.

That ground friction is even lower when you are looking at a train where the point of contact of wheels on the rails is much smaller than rubber tyres on asphalt. And it's even lower for maglevs, where the main friction is air drag. In general the rule of thumb for energy efficiency is: Trains > Automobiles > Planes.

Of course the advantage of flying vehicles is that they can generally get from point A to point B faster since they can go in a direct line, which saves a little bit of fuel, but mainly it saves time. So this will be a convenience thing, and making it economically viable from an energy standpoint requires you to have cheap and abundant electricity. This is also why we haven't seen personal flying vehicles take off as a commercially viable option until now with the progress we've made in EVs and electric batteries. Because if it was powered by fossil fuels it would be far too expensive.

Well...that and the advent of machine learning opening up the possibility for developing adaptive software which allows drone-like flying vehicles to maintain stability and fly autonomously or semi-autonomously.