Yes, nuclear is great. But the free market would deliver it if activists had not banned it. So your point about the profit motive being in the way of using efficient energy is not accurate.
I think you have a different understanding of “scarcity” as we do. We are referring to economic scarcity, simply meaning “not unlimited”. Even if we had replicators there would be scarcity, because we still have limited ability to bring goods to customers. You must be thinking of something like “exhaustibility” or “finiteness”.