The power limitation doesn't seem very difficult to surmount, a drone could just go swap its dead battery with one from a pool of batteries on chargers, and kee

The power limitation doesn't seem very difficult to surmount, a drone could just go swap its dead battery with one from a pool of batteries on chargers, and keep working. They'd need two batteries in a drone to do that of course, or perhaps some other robot could execute the battery swap.