I spent a long time ruminating on this awhile ago and came away very depressed. Deep down, I believe that human nature simply does not allow complex civilizations to live indefinitely. The interplay between selfishness which ensures individual survival and empathy which ensures survival of the species (thus indirectly increasing chances of individual survival) is tuned for sharing a living space with a few dozen other humans, not a planet of seven billion. Evolution found a local maxima sufficient to allow us to spread very rapidly, but it's not good enough for the state that we are in. Although advanced technology could allow a large number of humans to thrive, the lack of empathy will perpetuate an imbalance in resource and standard of living that, like a washing machine with an imbalanced load, will spin wildly out of control (and in this case tear itself apart).

I hold a sort of vague hope that a techno-Utopia is possible, but it's with the understanding that a great many cultural and political changes would need to be made first. Given that my talents lie in programming, I do my part in that arena and hope that others with an understanding of things like economics, security and human psychology will do theirs.