Automation and industrialization over the last 150 years already meant we went from 120h weeks on farms to 40h weeks in offices and factories, while living standards increased. Measured in 40h/week jobs per person that means we lost 2 of 3 jobs in the industrialization! The world didn't end. And now everyone is worried that if we go from 40 to 30h or 20h weeks that will be a disaster?
We can't afford to have a large fraction of the people unemployed and the rest still working 40h weeks in ever fewer jobs of course, but that's a problem societies will hopefully solve.