Honestly! If these jobs are eliminated, that's a wonderful thing! It increases the average work that the average worker is doing. This increases their average salary. This is not a problem!

The only real problem is getting these temporarily unemployed people an education and a new job. That's not a very big problem, as markets tend to make work when work is available. For instance, where did all the factory workers come from at the start of the industrial revolution? Everyone was working before then, presumably, as there was no such thing as welfare from the government. The workers came from industries that were torn down by the industrial revolution. We don't have cotton pickers anymore. We don't plow by hand. We don't have many of the menial labour jobs we had a hundred years ago, yet unemployment is less than 10% in Canada. The market equalized itself.

Where can these cashiers go? Perhaps preparing food. I wonder if we could start seeing more healthy restaurants that are more closely approaching the true cost of food at a grocery store. Since it costs less to have the store open, since the cash is automated, one could easily see that there would be more money available for food preparation.

The market will find a place for these workers, and everyone on average will see a net benefit from getting rid of non-producing jobs.

You're being optimistic and I hope you'll be right.

The big question is if we will be able to adapt fast enough, without erasing ourselves in a nuclear war or such.

Robots are just a different ballgame than the industrial revolution. The industrial revolution was mostly confined to the production-sector. A modern machine could replace a hundred workers with one. Robots on the other hand could very well erase entire industries, reaching far into the service-sector.

What do you do with hundreds of millions of humans who suddenly are not needed for productive work anymore?