[Thiez]

And what exactly would our hypothetical descendents do there, in the middle of nowhere with no star, no planets, and no energy?

[jeremyjh]

There are stars that are far from everything else and off-axis. There are even stars that get ejected from the galaxy all-together.

[ncmncm]

Yes, one of those last would be a good choice, if we could get to one.

But I don't expect our distant descendants to be dependent on starlight. A nice Kuiper Belt and Oort Cloud are good to stay in for access to building material and fusion fuel, but the most valuable resource, otherwise, will be abundant free cold.

Planets, as such, and sunshine are for the extremest primitives. Nobody advanced would want to be closer to the sun than, say, Neptune.