I was thinking something like this yesterday.

Assuming it could be done, one of two things would probably happen:

1 ) It would work, and life goes on.
2 ) It tries to happen, and fails because the human genetic code is too messed up from breeding and the ones who try fail because of it. While others who are "Made" better could pull it off can't (because we do have lives of our own).

Overal, I think evolution doesn't stop (a more accurate question is "Can it stop?"). So we will be constantly forced as an organism to deal with ourselves. So while extrememly probable that we will evantually have to move to another planet (assuming that we don't go exstinct), there's another way to stay on the planet: Keep it goin via Machanical means.
Sure it's an absurd idea, but it would be possible (assuming we had enough time and man power).

Although I think I've answered your question (while philosophizing a bit else) could you elaborate a bit more on your point? Otherwise yes, the human population could be considered as one big Organism, just like the Job Market.