Charlie Stross takes us 500 years into the future:
Looking forward 500 years requires us to make some assumptions. In the absence of breakthroughs in artificial intelligence, mind uploading, or longevity research (which it would be foolhardy to dismiss on this kind of timescale) none of us are going to be around in any form to observe it. We appear to be living close to the peak of a demographic bubble that will see our population max out or be in decline by 2100.
Now go read Diaspora.