But what if this time it's different? What if delegating everything to machines is a radical and fundamental new change in the course of human history?"
You could learn to repair the machines, or learn to make the machines.
Not if other machines repair the machines and make the machines.
However, we have seen it before and we will see it again.
Not quite. Just because it appears to have happened before doesn't mean that nothing changed or that there isn't an end.
In the pre-industrial age, most earned their income through brute labor.
Early machines took much of that away but there was still profitable tasks to done by trained hands doing the tasks that machines lacked the finesse for.
The factory automation came in, able to perform many of the many tasks that well trained hands previously did. It became difficult to make a living working with one's hands. But machines still weren't very smart and so people that were smart learned to make their living by using their brains.
But machines are getting smarter. They do brain work too and the kind of work they can do goes higher each higher. A knowledge worker can attempt to move up the food chain, of course, but eventually there will be no further up to go. If one can't profitable use one's brawn or one's brain, what is there left to do? Probably the last stand will be the artists. Human creativity feeding irrational human desires. Unfortunately, society has never provided many artists with a living wage.
Of course, this doesn't happen overnight or with 100% efficiency. There will always be a few people who someone make their living through archaic means. But there will come a time when most people will be unable to provide value beyond what machines are already doing.