The Taxibot system, where a small tug vehicle positions itself under the plane's front wheels, would be very promising if it could be self-driving and fully automated.

And think of the cost saving when we get rid of the pilot and cockpit. And heck, let's get rid of the landing gear too, and have the plane drop into a cradle running along underneath the plane on a track to catch the plane. The cradle would also provide a lot of the acceleration of liftoff, and the cradle's liftoff track could climb a few hundred feet like a roller coaster, so maybe the plane's engines could be smaller.