They will, as did monarchs in feudal times, draw their power base from the multitude of disenfranchised commoners seeking guidance, respite from the bleak outlook for those with little or no prospect of upward mobility, and a rallying point from which to focus any semblance of pushback against the landed baronial classes. But they will all the while be paying a hefty tax to those who maintain the broadcast infrastructure that enables them to marshall and monetize their followers, so even these kings and queens will need to stay in the graces of some potentate or other.
https://en.m.wikipedia.org/wiki/Kensington,_Philadelphia the Crime section
But you didn't mention the Soldier class. Some security people are needed, with an ok decent life, to keep the masses in check, and put up surveillance cameras and collect everyone's photos and biometrics
A bit like in Uganda, "Uganda's surveillance state is built on national ID cards" https://news.ycombinator.com/item?id=40603692
> Now, OTOH, if at that point, robot/AI weapons are sufficient so you only need 10 people to run the entire US Army.... then it's game over.
1. Supply drives demand. If nobody produces anything with which to buy the factory output, then the factories will not be valuable.
2. If most people are somehow living "outside" the economy, then they would form their own economy.
Those are but two trivial rebuttals, and by no means anywhere near exhaustive.
If with enough automation that's not necessary then it doesn't matter. Why operate a sneaker factory to get the money to buy caviar from the caviar factory when you can just operate the caviar factory directly?
Put another way, china thanks to it's new middle class is a great market for a business to sell to. That's because they have something of value to trade back.
But the Congo, full of people or not, isn't. They don't have anything any capitalist could want that would equal the value of finished middle class goods. All they have to offer is cheap raw materials or perhaps labor to extract. If people are made useless, we will all be from the Congo except the legacy capital owners, who can trade with each other for everything they might want.
Regarding #2, they would form their own garbage shit economy whose size and per capital size are like specks of dust compared to the main one, with obvious consequences for power dynamics when the two economies interact. Think of the underground economy in a prison, a homeless encampment, or a warzone, or subsistence farming peasanta deep, deep in thr Congo. Or the "economy" formed by insects trading pollen services for nectar with plants. That's how small and weak the economy of the leftover people with no access to the global industrial machine would be by comparison.
Look at life in Gaza or on the streets of Kensington today, and that is the sort of destiny we are bound for -- if fully replacing all humans really ever happens -- to become totally disposable people, who only continue to survive because someone has found it too much hassle to get around to getting rid of you at least just yet.
But that's an endgame state, it's not a path for getting there, thank goodness. I believe it would not be so simple. It would happen gradually, and it would engender resistance, eventually violent resistance once people have little to lose.
Power grows out of the barrel of a gun after all.
Now, OTOH, if at that point, robot/AI weapons are sufficient so you only need 10 people to run the entire US Army.... then it's game over.
But can you even get to that state without provoking a war before you get there? AI is extremely vulnerable in war because of its reliance on datacenters and fabs, which are fantastic military targets in wartime. So easy and quick to sabotage and so expensive and slow to build.