No one would work, no one would invent anything new, there would be no innovation, no increased productivity, so no further progress would occur, but by hypothesis we have reached a stage at wish further progress is not considered necessary. There would, presumably, be no money, because nothing would be exchanged. People would simply be provided with what they needed, according to some classification determined by their age and health, perhaps.
This would be healthy, comfortable society to live in. It would have no inequality, except that caused by the phenotype lottery. But would it be a nice place? I think not.
It would be rigidly totalitarian. Someone has to organise the distribution of goods and services, or tell the machines how to do it. And they need the power to stop anyone finding a way to live outside that system, or it would all break down. (That someone won’t be you or me, don’t imagine it will.) There would be almost no art, no competitive sport, little or no social interaction would be permitted. Such a society would practice eugenics pitilessly, to reduce inequality and unequal demand on resources (which are assumed to be abundant, but unequal demand would produce disharmony, and so would not be allowed).
There would be rebels, who either would or would not be eliminated. It wouldn’t matter whether or not they were stopped- they would exist, and between them and the means used to try to control them, life would be unliveable. I think I’d rather work.
I throw out these ideas with no serious reflection whatever. It just crossed my mind.