I'm in favor of colonization and expansion, within reason. I feel having multiple pockets of humanity is a good plan, in case anything goes completely bonkers here.
I think it's fairly feasible of a goal, though it will be long term, longer scale than most people are willing to actually operate on. The idea of working and funding a project that might not actually bear fruit in their lifetime, is fairly hard to swallow for a lot of people. It's why they never really get behind big changes to their behavior and lifestyle for the purposes of conservation, etc. When you tell them things like "if you keep doing this, things will go to shit in 50 years." they are like "yeah but, I don't give a shit about 50 years from now, I want my Mega Gulp NOW!"
But in concept, I think it's a goal we should have as a species, for growth, advancement, and hopefully enlightenment.