As ChrML said to me about NPCs...
Could be possible I guess but I wouldn't expect it to happen anytime soon...
What we'd need is a ton of people who want to do this and strive to make it happen. You don't want some guy going 110 in a sports car running up to your base and just shooting you. In the real world people don't do that... They plan out things, think ahead, spend days doing it, work out 'hits' on people and whack 'em. But without tons and tons of people where there would always be a balance (like if you have robbers then you need cops) it probably wouldn't work out.
I like your idea, Solid, but it just seems to go by too fast. I'd rather have things go at a slow pace, and not have to start a new game every hour.