[Baeocystin]

I think this is a particularly salient point.

Earth is already well on the backside of how much longer it will be hospitable to life. First life was ~4 billion years ago. First multicellular life, 1.5. And now here we are, the first intelligence of our kind, clearly closely related to the animals we descended from, but just as clearly different in how our minds work.

That's one example in 4 billion years, and the Earth has between 500 million to 1 billion years left before the ever-increasing brightness of the sun boils the oceans and sterilizes the planet.

It could easily be that life is stunningly common across the universe, but that 80% is at the level of bacteria, and 99.x% is simple animals at best.

[swombat]

My understanding from Astrophysics class back at uni was that sun-like stars spent 5-10b years on the main sequence, so I thought we may well have another 5b years of quality sunshine to enjoy. Or not.

[Baeocystin]

You're right, in terms of the sun's ultimate lifespan. Unfortunately for us, the Goldilocks Zone is very sensitive. To achieve full solar sterilization of the Earth only requires ~10% greater output from the sun, for example. And that will happen long before the sun leaves the main sequence.

To give you an idea of the timescales involved, at the very birth of the solar system, right after the Earth coalesced, solar output was approximately 70% of what it is today.

It's not quite as bad as it sounds- if there is technological, intelligent life on Earth a billion years from now, simple diffraction gratings at the Sun::Earth L1 point could stretch the remaining time for hundreds of millions of years. Not something we can currently achieve, but it is within the realm of possibility. Beyond that is pure speculation.

https://en.wikipedia.org/wiki/Space_sunshade