Now that commercial interests have taken to space flight I think we’ll see a lot more advancement in the next 20 years than the last 50.
I don't disagree with that. I'm not sure what about Mars would make it commercially viable for colonization versus a few manned outposts for research.
Even if there are resources on Mars for commercialization, they could probably be best extracted by robots without the need for colonies.
It would happen more quickly if living space were to become a precious commodity.
Even if mining robots are the main inhabitants of Mars, people would eventually follow. Someone has to repair the robot - that repairs the robot - that repairs the robot - that mines the materials. And the people who repair robots will need goods, which will set up secondary markets and populations. Indeed, replace "guy who repairs robot" with "gold miner" and you get a repeat of how Northern California became populated.
It probably won't happen as quickly, but it will eventually happen. The Matrix's Agent Smith had it somewhat right when he called humanity a virus - we seem compelled to continually spread and propagate.