With the current power structures in place, assuming AI can really do all labor, why would the people in power keep us around then? What for?

They probably wouldn't go for the mass murder option right away because of the logistics issues and possible revolts but there is no reason to keep excess population around long term.

Yes, technically, they could realize that there is enough wealth for everyone now. They will not. The problem with capitalism is that it can't stop. They will try to accumulate more and more wealth until the planet is destroyed.

We will see the future that Start Trek promised, eventually. If humanity does not get wiped out before. But what is coming first will be a wave of bloody revolutions, it will not be pretty but necessary.

Thankfully we probably have quite a bit more time than five years left, realistically.

For humanitys sake i would argue.

But yes it will be very interesting if we don't reach any ceiling if another fitness function than "more money" will arise or not.

I think the story "Manna" describes pretty well what will happen if AI and robots do all/most work. People will basically be pushed into welfare buildings and receive minimum support to survive. I don't think the capitalists will share the wealth voluntarily. If they wanted, they could do that already, but they don't.