This is not optimistic, this is very pessimistic.

PoW requires unbounded use of resources, which can and will scale up very much, even over the point of "no profit".
I'm not only talking about the energy used, but also about the old miners produced and thrown away.

We might end up realising PoW is the one and only "way to do that" (though I hope not), but that would be a very grim discovery.

PoS is environmentally safe.
Maybe it works, maybe it doesn't, maybe it will improve.
Maybe something else entirely will come (Proof of Burn anyone?).

In the end, if any safer method wins, it's better for everyone.