I imagine that the APU generator must be reinforced or redesigned to be able to withstand the charge of the motors. Revereser are quite efective and I don't thi

I imagine that the APU generator must be reinforced or redesigned to be able to withstand the charge of the motors. Revereser are quite efective and I don't think you can get rid of them, because when you have slippery runways the braking through the wheels is going to be compromised. It's also another sys to fail on toP of the normal braking system (that already has quite a bit of it's own problem), so it's better to have paralel systems for the same function. If you are going the active braking route you'll need a place to send that electricity and the actual batteries are not big enough for that. You are right that the motor are not very powerful, 20kts max is a bit on the slow side as top speed. Given that in a big airport when you taxi at less than 15 kts you are slowing the rest of traffic (and they get nervous indeed when they are following a turttle!). Also to really be autonomous with this sys I imagine they'll install cameras to see the rear and the engines's nacelle (to be able to see that the engine is starting without issues, witha normal pushback you have ground crew observing). That's another level of systems that need new procedures and testing, not very complex initially but things can become really weird very fast in aviation and all unusual user cases must be taken into account. Edit:phrasing correction