[jerf]

"even after you've completely destroyed the economy.... Can you think of ways to use your fleet of killer drones for maintaining your position in power?"

It is worth pointing out something that a few modern-day tyrants have already discovered to various degrees, which is that the tools of modern oppression require modern economies to keep functioning. If the economy is "completely destroyed", the drones aren't working either. They require power, maintenance, replacement parts, replacement drones, technicians to manage the gear who will need to be fed (and who will be in a position to turn on you), etc. Mind you, small comfort, but a bit of one.

[jmcmichael]

There's nothing preventing the inputs required to keep the drones going - power generation, parts, repair, etc. - being automated exactly the same way as every other facet of our economy is being automated.

[jerf]

If we're to the point where that level of automation has been achieved, it will not be drones in the sky that are your biggest problem. I'm sticking in the forseeable future here, not near-Singularity future.