Steven has an interesting post on his blog, where he discusses how technology that is repurposed as weapons will bring about some unforeseen consequences. His specific example is how the terrorist group ISIS claims to be assembling an air force out of radio controlled drones. Not the military versions that have existed for years, but the small ones you can buy in convenience stores around where I live.
Consider for a moment. It is possible, though extremely unlikely, that drone technology and control software will become so sophisticated and cheap that people of moderate wealth could one day own swarms of drones in order to safeguard their own homes. A few could fly aerial patrol overhead, switching off with fresh machines when the batteries are low and they have to go back to their charging stations. If an anomaly is detected they could alert the homeowner, or even just call out the armed drones to attack.
Reminds me of some libertarian science fiction I came across back in the 1980’s and 1990’s.