I think there will be plenty of work for a while because manual labor - construction, healthcare (doctors, nurses), food preparation, tradespeople - will be hard to replace in the foreseeable future.
I see UBI as a solution to inequality (real problem) not as a solution to lack of jobs (not a problem). AI will probably lead to reduction of inequality and therefore there will be less need for UBI.
In theory, the "mental" workers who get replaced by AI could simply move to manual jobs and total production and average wages would go up. But they may not like it, at least I wouldn't.
Total production would increase (AI will allow us to make more with less) and I'm expecting the capital / labor share to remain stable.
An analogy:
Imagine that half of the labor force makes cars, the other half creates software. The average person buys 1 car and 1 software per year. There's a breakthrough, AI can now be used to create software almost for free. It can even make 2x more software per year. The programmers switch to making cars. So now the economy is producing 2 cars and 2 softwares per worker per year! Salaries have now doubled thanks to technological progress.
You could argue that this will increase inequality and all of the productivity gains will go to the top 1%. I don't think so.
Manual labor has been my general thought but the progress Tesla is making on their robots makes me question that assumption. I imagine in the next decade, we're going to see large swaths of the population unable to do meaningful work that isn't already done by machines.
We're looking down the pipe at a truly dystopian future.
AI will increase inequality, because most jobs will be automated, & most people will either not have jobs or have incredibly menial physical jobs where they are interchangeable
I see UBI as a solution to inequality (real problem) not as a solution to lack of jobs (not a problem). AI will probably lead to reduction of inequality and therefore there will be less need for UBI.
In theory, the "mental" workers who get replaced by AI could simply move to manual jobs and total production and average wages would go up. But they may not like it, at least I wouldn't.