A moon base, space colonization and asteroid mining are much more realistic and actually achievable goals. The technology is mostly there - the hard part is getting someone to make the effort and spend the money to do it.
This is a very interesting read regarding this topic, though I'm not sure if it's publicly available at the moment.
Although in many documentarys it's been said that the sun will penetrate earth hemisphere and there will be unbarable temperatures on earth, that leads us to our only chance in saving ourselfs, moving to the moon. But I don't get that because the moon moves around the earth and on one side of its rotation it would be unbarably cold, on the other side we would melt probably. So either way it's going to end in a fire
Moon will most likely to be used as a forward base for future space programs. With very low gravity, you can launch much heavier spacecrafts with all the equipment you'd need for a long mission. Mining operations in Moon would only serve the purpose of supporting this kind of colony, there won't be any money to be gained from mining a distant rock that has identical mineral layout to the rock we're standing on right now.
To put it in perspective, it won't happen in millions of years. By the time sun reaches the point where it expands and burns out, human civilization has either died off or expanded all across our galaxy.
More on topic, I don't see why people is so scared about the end of the Earth and the humanity as we know it, it's maybe the best thing that can happen to the universe, we're not that good
To the living being which would substitute humans I don't know, that's just one of the millions of ideas and theories that came to my mind before posting
Actually no, the idea is not to go to moon, harvest it's resources and bring them back to earth. It would be quite silly since you can find all that stuff already on Earth and I don't think we're thirsty enough to spend millions for one bottle of moonwater. But this works otherway too, sending supplies to outer space is very expensive, having them right there on moon would make it cheaper.