Instead of a guy with an AR 15 at a grocery store, it'll be 50 drones at a NASCAR race, exploding in the stands.
Killing a bunch of people with drones is actually harder than just getting an AR-15 and killing a bunch of people and will likely remain that way for a while.
But it's different with killing a cop. It's hard to kill a cop because they're armed, and it's even harder to get away with it because the cops will be ruthless in tracking you down[0] but a drone changes that dynamic.
Police can be so corrupt in the US because they can get away with it. It will be fascinating to watch how they react when someone uses a drone to kill the next cop that walks free after brutally killing an innocent person.
[0] https://en.wikipedia.org/wiki/Christopher_Dorner_shootings_a...