What a dark thought. We have billions of years, or atleast 1 to figure out a way to either perserver Earth or control our Sun. While I believe this not to be impossible, you probably wont see this until a lot about the human race becomes different. While we could just move from planet to planet while the sun gets bigger as a way to survive we could also in that time colonize much more than just our solar system, which we would no doubt always call our true home. We are in the tails of our galaxy the collosion with the andromeda wouldn't really affect us to much, though it would bring much more life to our galaxy.