Here's a fascinating essay by the inimitable Claire Wolfe on the importance of frontiers as an escape valve for societies. She points out that human beings have always looked over the next hill or across the next river as a way to start over or find greater freedom. Unfortunately, the world is filling up fast and there aren't any frontiers left. Even out-of-the-way places like Alaska and the American West are pretty darn civilized these days -- and that civilization includes all the usual accoutrements, such as mounds of paperwork to fill out and busybody bureaucrats to satisfy. The few semi-successful freedom movements on the planet keep bumping into big governments of one kind or another, and it's unlikely that a small state could successfully negotiate greater freedom within the USA (as the Free State Project wants to do) or even that a small nation such as peaceful and increasingly-libertarian Costa Rica could long evade the ever-lengthening tentacles of the modern Octopus whose body is centered in the District of Columbia (oh, the imperialists would find some excuse for intervention, probably something about not prosecuting the War on Drugs fiercely enough). What are the inhabitants of a crowded, highly-governed planet supposed to do?
I know it sounds far-fetched, but the best answer in the long term is to find a truly new frontier, which means we need to look up. The options? As Claire Wolfe points out, space stations in L5 libration points (once popularized by the L-5 society) are one. Mars colonization is another (check out Robert Zubrin's books The Case for Mars or Entering Space for the full argument, or visit the Mars Society). Heck, just today came news that Mars may contain a lot more (frozen) water than anyone previously thought. And given the fact that there are 434 known Apollo objects (a.k.a. potentially hazardous asteroids), we would do well to split up the herd and seek long-term survival in habitational diversity.
Speaking of which, I wonder why so many SF novelists concentrate on the far future (FTL travel and all that guano) when the medium term offers so many more interesting times: L5 societies, Mars colonization, asteroid mining, and the like. Of course, it could just be that I need to read more SF novels. :)