I think taking humans out of the equation when it comes to some things is good. Lets face it. Humans kind of suck when it comes to running a stable and healthy civilization for ourselves and the planet. We need a higher intelligence to solve some the issues we face, whether its climate change, disease or poverty. The best outcome with A.I. is that it could eliminate the need for most human labor, while simultaneously providing abundance for everyone the planet. We'll have to figure out new ways of being and it will inevitably cause some problems. Especially for those who've come to identify with their work/profession.
I don't think extinction is something to worry about if we align A.I. successfully. And even without A.I. we're headed for collapse due to climate change anyway. IMO A.I. is one best shots we have to avert human extinction and collapse.