one of my pet subjects - look up posthumanism in google. Personally I think we will have transferred our consciouness to huge fusion powered machines capable of faster than light space travel. The human body will be replaced within a few hundred thousand years. The development of ex-vitro fertilisation will also allow humans to be born with bigger brains as there will be no limit imposed by the female birth canal. Illness and disease will disappear, food will be plentiful, we will have beaten both the AI machines and the insectoids and everyone will be able to read and write . . .
You guys aren't thinking big enough ;)