Again, if they send people to Mars, they are NOT going to send them unless they have some provision to return them. That would be awful PR and simply intolerable, since it would be paying people to commit suicide. The more publicity they used to get funding, the harder it would be to send them on a suicidal mission.
The first manned mission to Mars would not be a colonization attempt. And I would imagine that it will take a long time before any such mission happens.
I think that NASA is doing a fine job at present, with the robotic and satellite missions. We have learned more from these than the manned missions. The first Moon missions were not mainly for scientific purposes, they were basically ego trips. That was not necessarily a bad thing, but we do not need to repeat the same sort of thing on Mars.