I didn't say that we actually are post scarcity, only that we could be if that were society's priority. Take away all the useless work, and that doesn't leave a whole lot to require coercion. Most of our food production is already pretty much automated, and most of the rest would be if coercion was taken off the table.

I don't share your optimism on fusion, but that's not very relevant since there are other technologies that I see as long term solutions. We also waste tons of energy, for instance Bitcoin alone is estimated to account for 2% of US electricity use.

I don't think it says much for communism as an economic system if all the economic problems have to be resolved before it becomes possible.