There may not be post scarcity as there will always people the desire more and thus commerce will exist. However that doesn't necessarily means that everyone needs to contribute to that economy. If we have developed the technology to allow for basic food, shelter, and healthcare then people who don't strive for anything more should be able to acquire these things without additional work and become a basic right. In my mind the idea of basic work isn't to stop people from working, it's to stop requiring it for basic livelihood.