Unfortunately that's not how it works. Productivity gains have already increased tenfold in the past, yet still all work full time.

It used to be that 80+% of the population worked in agriculture. In developed countries that number is now around 1-2%. Some of the freed labour was funneled into improving living standards, some of it was funneled into new jobs created by the increasingly complex society (the "intermediate economy").

With AI, the same is true: labour is freed by the productivity gains (which I doubt are 10x sustainably but whatever), more labour is needed for power generation, mineral extraction, maintaining this new extra layer of complexity in the intermediate economy, etc. In the end we might see, say, a net 3% increase in global productivity per year over the next 10 years, which will be funneled into increasing living standards and increasing economic inequalities, but not in reducing working hours.

If you accept living below average standards, you could easily work a single day of the week for the rest of your life. But why would an employer hire 5 people working one day a week, instead of one working 5 days a week? They won't, hence we don't see a reduction in working hours.

The alternative is to work full time but retire earlier, much earlier, than you would otherwise, which in the end is the equivalent of having worked one day a week for your whole life.

I highly recommend reading Lean Logic by David Fleming, it explores several of these concepts in a very interesting way.