rickb wrote:
Eventually the Sun will go supernova as well. If humanity wants to survive we're ultimately going to have to find other planets to live on. Off hand, I'd say rebalancing human life on 4 planets might work fairly well.

That's great.
If you look at our space adventures thus far, however, in the past three decades our manned space program seems to be going backwards.
Looking forward, I don't think more than a handful of humans will ever leave the earth's orbit (I would be happy to be wrong about this, though).
I once did a calculation of the amount of energy expended to build the pyramids and found that the first manned moon mission consumed approximately the same amount of energy that was required to build the largest of the pyramids in Egypt. I thought this was interesting because both of these accomplishments were, in a sense, monuments erected at or near the height of each of these cultures and civilizations.
It sort of tickles the imagination to think about 1,000 years from now people sitting around and telling stories about humans who visited the moon, and how the story could be perceived as pure mythology. Unlike the pyramids, there is no lingering reminder that the moon missions actually took place, which makes it that much easier to convert the events into mythological narratives, with appropriate embellishments here and there (e.g., Neil Armstrong might become a Zeus-like figure, while Buzz Aldrin could be Poseidon).
If you've ever studied "cargo cults" (or watched Mad Max: Beyond Thunderdome and remember the kids who lived at the airplane crash site), you know how very easy it is for people to convert the accomplishments of industrial capitalism into supernatural events. It's probably not so far-fetched to think that our own descendants might do the same thing with the wonders of our current world.
One requirement for the kind of mythological-ization (I just made that word up) I am describing would be a massive loss of knowledge between generations. One catalyst for such a loss of knowledge could be an EMP event at some point in the future when most of human knowledge is stored electronically (as opposed to on paper, as much of it is now).