What do you mean? The expansion of the sun, or a meteor strike, or a caldera explosion, something like that? Well, yes of course those are all likely on some large time scale, but they are entirely out of our control. Meanwhile we have every likelihood of having a 1M year existence, as a species embedded in a biosphere, if we can "get on the same page" with respect to our behavior. I propose that we adopt the universal rule that we all act "consistent with our survival, and that of our species" in an exact analogue to Issac Asimov's Zeroeth law of robotics. It is a small jump from that to the protection of the biosphere in general, if you are willing to ignore the strong emotional pull of science fantasy narratives that imply that we can survive without it.

There's just absolutely no evidence to support this statement. We don't know enough about meta/xeno-biology to say that life isnt a self-sustaining phenomenon in a thermodynamic sense. It may be that human-like "intelligence" is actually an emergent phenomenon, not unlike cancer, that has the potential to disrupt an otherwise homeostatic set of processes.

I think he was referring to the eventual expansion of our star such that our orbit is smaller than its diameter. Of course that's no excuse to be a jerk in the meantime.

Well, our sun will eventually explode, which will certainly chew up the biosphere.

The sun will make Earth uninhabitable in a billion years, give or take several hundred million, and depending on how long extremophiles can hold on.