The use of Tethered uav and drones is being explored and results so far are encouraging. Power goes up the wire so fewer batteries needed.
I see a can of regulatory worms labeled manned, powered, tethered flight
Another can of worms, do regs cover a commercial, fare paying passenger flight, which is controlled via tether by pilot on the ground?
Enormous redundancy can be built in at a minimal penalty...
Mickjoebill