At the moment we can see that there are problems with capitalism, but the system is working for enough people that it can endure without too many problems. Obviously the system has been in permanent crisis mode since 1929, it stopped working without massive state intervention and police force to maintain it a long time ago.
When capitalism stops working for the powerful, when its inefficiencies and contradictions become wholly intolerable and beyond the ability of state intervention to contain, then you'd have the conditions for something different.
It has nothing to do with post-scarcity, and post-scarcity is a dumb meme anyway. Shit is always going to be scarce in some manner, even if you cut human population down to 500 million there would be fights over all the stuff in the world. Nor is it really possible to get away from human labor entirely, not for the forseeable future, since you need people to build and oversee an AI to make sure it conforms to human needs (unless people are really really stupid, they will want to do this, because Murphy's Law is always a thing with technology).
What is actually happening isn't that ze robots are taking over, it's that there is a limit to how much shit people can produce profitably, and businessmen have every incentive to sit on hoards of cash. Further, the financial system is sitting on a house of cards, and actually doing something with America's supposed wealth would expose just how much the financial system is inflated, never mind the ridiculously unsustainable debt that can not possibly ever be repaid. Even if the computer had never advanced beyond the old vacuum tube contraptions of the '50s, you'd have seen the same trend towards unemployment just because the growth of the mid-late 20th century was a temporary condition. It has been happening all along - the state has become really good at distorting it's official statistics to hide mounting unemployment and crises, to the point where the official 4% rate is laughably divorced from reality. Yet, the hoards of wealth are so vast that the system could keep trucking with 20-25% unemployment and few would notice, aside from the people who are falling into the dregs of society and know instinctively what that means with great dread.
My guess - I don't hang around a lot of techpriests - is that a lot of these people are on the meritocracy bandwagon, and have no interest in the idea of sharing the wealth. It's not so much a blind faith in capitalism (that's for idiots), but a deep-seated hatred of those they consider beneath them. Currently, capitalism sufficiently justifies their hatred, but it was always about the hate, rather than a belief that the system is genuinely ideal. When it comes to their bosses, they would be all for seizing wealth, but they would want it in their hands as a class, so they can rule instead of the bourgeoisie. There is no space for class abolition and the proles are either irrelevant or only useful as temporary shock troops at best.