* Human capability >> robotic capability
* Mars as a very long term "Backup Earth"
* If you can go to Mars with humans you can go to the Moon with humans as well.
* Human capable systems can also carry robots, the reverse is not always true.
1) If we can live on mars, we can live on whatever state earth would be in, even if it was mars-like.
2) If earth becomes unlivable, the exhaustion of resources would mean we'll never be able to get to mars in the first place.
Either way, I just don't see a mars colony happening as anything except a temporary experiment. It's a really hostile environment.