But if you say there will be multiple people with big space ship fleets - sure, that's cool too!

Speciation happens anyways.

There's 8 billion people on the planet already and something like 80% live in developing countries. There are massive productivity gains to be had as those people improve their education and move into more productive jobs.

Growth has its limits. It is generally sigmoidal (S curve), not exponential. It’s reasonable to assume we’ll hit the inflection point long before the sun becomes a problem.

My point is that we’ll need to find an equilibrium that doesn’t rely on continual growth, because that won’t be sustainable. After we manage that, there’ll be still enough time to worry about the sun. And if we don’t manage that, human life on Earth will be doomed regardless of the sun.