> Humans living forever is inevitable. Galactic colonization, inevitable. Over a long-enough time scale.

I doubt that. I think we just fizzle out. The survival of the fittest instincts that made us a successful species is destroying us as we are getting more capable. Our 'leaders' are getting ever more unhinged.

And without faster than light travel there just isn't much point in galactic colonisation. If generations have to live and die in a tin can to get to some remote star, why not just live in that tin can in the first place.