Those are some fine points.

Indeed, money itself keeps social classes separate because money's countable, so some people can have more of it than others. But what gives fiat money its value? Ultimately, I think, it's trust in the system. If machines and computers eventually take over most people's jobs, I suspect that that trust will be lost. Power will shift from people to the machines and the AIs. Money might then be as useless as people's bodies and minds.

There are always cracks in a system where deviant subcultures can flourish. As you say, not every job is worth standardizing, but even those that aren't automated might potentially be so, in which case they still lose their worth. The humans who perform those jobs that aren't even worth automating won't have the same respect as the craftsman who amazed their neighbors before machines were invented that could have performed those tasks in a nanosecond.

Much of this is psychological. The power differentials aren't all physical. It's a question of whether the humanistic myths will always support our pride in our progress.