> I'm personally more concerned about potential chemical, biological, and nuclear warfare, against which there's really not much that people can do, and which might eventually become as easy to perpetrate as conventional drone attacks (and might even be facilitated by them).

I think most of that concern is misplaced. It will never be easy for non-state actors to conduct nuclear warfare (unless you count inefficient small scale radiological attacks) and while a sufficiently dedicated group can synthesize chemical weapons, it's easier and generally more efficient to just build a big truck bomb (or ten). Biological warfare is more complicated, both because it depends on your definitions (it could be said that every person stupid enough to go to work with the flu is engaging in biological warfare, they're certainly doing more damage than all the world's terrorists put together ever have), but also because that's the one area where rapidly developing technology really could have a huge impact in the near future.