[jyl]

It is an interesting question.

Let's say, hypothetically, that technology advances to the point that only 10 MM people are needed to feed, house, clothe, entertain, educate, heal 300MM people.

What will the other 290MM people do? If they learn to do the jobs of the 10MM, then demand/supply will drive down wages for the 10MM jobs. If they don't, they won't have any way to earn a living.

Options will include 1) let 290MM starve and when they start rioting, shoot them; 2) provide the 290MM with a subsistence income; 3) create more jobs by converting full time to part time or reversing automation.

Centuries ago, people left England to settle in America for analogous reasons. We can't send 100MM people to Mars.

Plenty of sci fi explores options 1) and 2) in dystopian futures. I don't know of any sci fi that explores option 3). But it could be done. For example, suppose we outlawed factory farming, so that food is again grown by small farmers (organic, no doubt). Agriculture would become a significant source of jobs again.

It's not, I think, an issue we'll face in the next couple of decades. But it might well be an issue in our children's lifetimes.

One possible result is that society will have to deemphasize efficiency and thus corporate profit. Left to its own devices, profit maximizing companies will always try to employ as few people and as many machines as possible. Letting 290MM starve will be profit maximizing in the short run, so that will be the result in a purely capitalism, private industry, free market economy.