Although we can't know what the economic system will be like after the day arrives that AI & robots can do all work (even future uninvented jobs), but are always getting cheaper than us - it's safe to make some guesses.

This is a policy document from left-leaning progressive economists, and it only mentions UBI to say it not the right strategy. Instead, they recommend the government take control of creating new jobs. Some people assume UBI will happen, but I wonder if the outlook in this report is more likely.

I'd guess the first response to this issue will be a compromise between right and left. Those on the right will want to prevent a collapse of the financial system, preserve the rich's wealth, and maintain at least a pretense of free-market economics.

We'll get to a point (probably a systematic financial crisis like 2008) where the right will be forced to do something to protect the wealthy. Which will they agree to first - UBI or government-created jobs?

I think it's a strong possibility it's the second option, and enough left-wing politicians will be happy with that so that UBI gets pushed to the background.