Perhaps Anon will build their own drones to take-down government spy drones?
Or imagine a worldwide, anonymous, crowd-funded assassination network funded by bitcoins; targets decided via user votes and hits performed by weaponized drones that have no trace. They could even simply be suicide drones packed with explosives, controlled autonomously to fly at a target via face recognition.
...aaaaaand now I'm probably on a watchlist for typing that :)
PS: Problem #1 people don't look up that often. Problem #2 there are a lot of people walking around out there. And it just get's worse from there.
Say IED builders in Afghanistan, probably do not have PhDs in physics and chemistry but they can build effective shaped charges to pierce thick tank armor.
So at some point you could just order parts from some place. Assemble, then upload the picture of face it needs to recognize, approximative coordinates and press the "take-off" button.
As for facial recognition software, there's probably already an Android app for that. Sure, there's a lot of work involved - it has to recognize the person, it has to drive around autonomously, it has to aim and fire. But most of those may be pluggable components of hardware and software soon, coming from perfectly innocent projects.
I think drones may well be a big problem in the near future.
This would be the same criminal underworld that currently builds 60-foot submarines?
Think China sending a drone and using it to assassinate the the president. Make it fly away and destroy itself over water or some other place where it won't be recovered.
Later on it might be possible for people like McVeight to use a drone to kill the president rather than blow up a federal building.
There seems to be a broader trend where our offensive technologies are moving much faster than our protective systems. At a state level, this has been handled by deterrence. Fortunately, for nuclear weapons, the necessary materials were rare enough for regulation to be possible. But deterrence wont work when these technologies become popularly available. Hopefully, there is some non-brutal solution that we can find for this problem.