If there was truly no scarcity - of land, of mineral resources, of labor... maybe we'd have something close to a socialist utopia. At least it would be possible for it to function in theory. There's still the human element which is always prone to becoming corrupt. One thing that will always be scarce is human good will.

I think the idea of a post-scarcity world ever existing is really far fetched though. Maybe after some mass extinction event when humanity is reduced to the tens of millions but somehow manages to retain most of its technology. Or if we ever master space travel and spread throughout the universe and achieve faster than light travel. Both are pretty much science fiction stories. I don't think 8+ billion people could ever have it, it's already clear that is way too many people to live a first-world lifestyle so half the world's population lives in poverty.

So any socialist utopia on earth would have to have some population control to ensure that renewable resources are not used faster than they can be renewed, and that finite resources are able to be distributed equally or at least in a balanced way without hitting the limit.