That isn't anywhere near enough to cause extinction, and the vast amounts of resources, engineers, scientists, etc required to do that would be much better spent solving those problems instead.
It absolutely will matter, because in the course of those generations, people will die or suffer or both. I'm talking about triage. We don't need to worry about the sun exploding just yet.
In that case it would be more rational to spend money on asteroid detection and deflection. That would be orders of magnitude cheaper and easier than building a completely self sufficient space colony.
Your self-sufficient space colony can still be destroyed by asteroids too, so that doesn't solve the problem either. Deflecting asteroids is entirely possible so it isn't a "patch" either. And building a self-sufficient colony would be so ridiculously complicated and expensive, it might not even be possible at all. That sounds more like a "patch".
