They're pretty low. We don't have the option of moving to Mars. Dear Mr. Sherman, I often feel like a fish out of water when discussing issues and prospects with sociologists. I happen to be, in this sense, an average historian. Although I certainly concur with world-systems theorists that there are trends and cycles in human affairs, I do not believe they are unevadable, and I do not believe that the same things ever literally happen more than once.
Circumstances are always somewhat different, leading to somewhat different outcomes.
To me, history is full of surprises, nasty, pleasant, or whatever. The earth is not an anthill, and human beings have choices.