Alarmism aside, there are ways to mitigate this outcome. Take your comment:
>or human labor will be cheaper than a robot replacing it
One option is to create an automation tax, which makes human labor more competitive while also supplanting the income taxes that are lost due to automation. That's just one example, but like so many problems that are of man-made origin, there are also potential solutions of man-made origin. They are not natural laws.
Since everything is going to get automated, this is one of the more complex ways of getting to the same place: industry taxes that pay for a universal income.
My take is just as radical, but makes more philosophical and moral sense (to me).
All newly discovered non-human made resources are considered a common inheritance. Industry (whoever) gets bounties for discovery, and bids to extract, with that money getting distributed to everyone evenly.
What I like about it: inheritance is considered a moral transaction, joint inheritance of the planet is an ideal we often give lip service to, flat distribution does not favor or disfavor anyone, and this distribution method doesn't take anything from anyone (after a gradual transition to the new regime).
The value of total natural resources extracted is going to increase over time, even as unit pricing goes down. Access to resources beyond Earth will give the value of new resources a big boost.
Something will have to radically change, regardless.
> One option is to create an automation tax, which makes human labor more competitive while also supplanting the income taxes that are lost due to automation.
As if those in power would ever agree to such a thing. "Trickle down" is a myth, US Congress has been gridlocked for decades, and most other parliaments in the world are so infested with lobbyists that you will not ever see an automation tax without widespread violent unrest. People living outside of democracies have it even worse.
There are zero signs that democracy is capable of fixing the issues at hand, it's all just too damn corrupt, and fighting for utter and bare survival against the rise of authoritarianism. Yes, you sometimes have "social democrats" gain power (or authoritarians getting booted off their posts like PiS in Poland or what will sooner or later happen to Erdogan and Netanyahu), but they spend almost all of their political energy on undoing the worst "accomplishments" of their predecessors, and all too often get booted themselves by a population unwilling or financially unable to go through change (as we're seeing in Germany).
>or human labor will be cheaper than a robot replacing it
One option is to create an automation tax, which makes human labor more competitive while also supplanting the income taxes that are lost due to automation. That's just one example, but like so many problems that are of man-made origin, there are also potential solutions of man-made origin. They are not natural laws.