I strongly disagree with this. We have several hundred million years left, and we've only been around as an intelligent civilization for what, 100K years?
200 years ago nobody would even think of flying on Earth, and yet here we are, taking it for granted that you can get almost anywhere on this planet within 24 hours for a couple thousand dollars, and within a century of inventing the car we landed a robot on freaking Mars.
Now I do think that we will take charge of evolution and invent a form of life that will be our successor to withstand a much harsher range of conditions and absent from the "bugs" of current life such as cancer and heart disease, rather than our current unreliable meat bags, but we'll make it happen nonetheless.
All that said -- I do want to see more attention toward terraforming Earth as well. Even with zero global warming, the sun's brightness will increase such that our oceans will boil away within 1 billion years, even though it won't actually engulf the Earth for another 4 billion. I would think it's realistic to extend the habitable period of life on Earth from ~300 million years to maybe 2 billion years with some terraforming tricks. That will buy us more time to terraform Mars or Saturn's moons in preparation for the red giant phase of the sun.
Also, learning to terraform the Earth can reverse global warming, because, you know, politicians don't give a fuck about stopping it, so we should attempt to learn to reverse it as a backup plan while the political environmental efforts continue in parallel.