In any case, I think humanity's ability to survive the future hinges on creating a space elevator (which currently we technically have the technology to do, although I think it still needs some development). If we don't make one, we're stuck with the massive costs of space travel, which probably means we'll just keep dropping satelites, and doing scientific missions. What concerns me is all the questions of making one, can we even keep it up there without the weather breaking it? Or debris smashing into it? If it's inevitable, how long will it take? What's the gamble? There's a chance we might not actually make it into space before our resources here are exhausted. They really aren't infinite, and we're going through them pretty fast.
Another thing I'm interested in is what mars would be like to live on. Considering it has ~1/3rd the gravity of earth, I don't know if it could sustain an atmosphere people are capable of breathing for extended periods of time (of course hab domes are more than possible, but that adds a whole bunch of difficulties... which can be overcome).
And then there's the question of what that gravity would do to human development. Zero-G is horrible for your health, how bad is 1/3G? Can you live in 1/3G? What's the life expectancy on an overgrown martian... I think genetic engineering could take care of those difficulties... it is of course a pretty sure bet humanity will one day no longer be humanity.