Oh, I see - sorry!
I looked into who was going to win such a bet.
http://en.wikipedia.org/wiki/List_of_assassinations_and_acts_of_terrorism_against_Americans
...looks like a reasonable resource on the topic.
I'm not sure that the acts of a single person with no associations with anyone else are really the sort of thing I had in mind, but it's too late to refine the bet now, so we'll see whether people think such a thing counts if we need to.
I would like to propose this as a thread for people to write in their predictions for the next year and the next decade, when practical with probabilities attached. I'll probably make some in the comments.