In a recent lecture Stephen Hawking said that although the chance that Earth will eventually succumb to disaster is very high humanity could nonetheless survive because by that time it may have colonized outer space. Certainly, this might not be the case if there were a nuclear war in the next 300 years or so. Reasonably, even if people survived a nuclear war in the next several hundred years they might be in no condition to develop the technology to afford self-sustaining colonies in outer space. Hawking optimistically (in my opinion) thinks people might have such technology in the next 100 years. Per the article:
“Although the chance of a disaster to planet Earth in a given year may be quite low, it adds up over time, and becomes a near certainty in the next thousand or ten thousand years,” Hawking said during his first BBC Reith Lecture, that will be aired on Jan. 26. “By that time we should have spread out into space, and to other stars, so a disaster on Earth would not mean the end of the human race. “However, we will not establish self-sustaining colonies in space for at least the next hundred years, so we have to be very careful in this period.”
300 years for us to colonize other planets? Jeeze, I hope not. I hope it doesn't take that long for us to get our shit together. The disaster within 10,000 years sounds like a possible thing.
The general point he's making sounds about right.