It will turn out that PoW is absolutely essential. Everyone will go "a ha" and that will be the end of the debate.
(I might be a bit too optimistic...we'll see...)
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.
Proof of cold can be used to at least mitigate if not eliminate the environmental cost and in fact to increase decentralization in a POW system. In a POW system if a use is found for the "waste" heat, and that use is only of value if decentralized, then the security of the network is still maintained. Proof of cold means putting the waste heat from proof of work to good use by displacing the energy otherwise used for space heating in cold climates. So for example a transaction in Melbourne, Australia where it is say 30C in January gets secured in Winnipeg, Canada where it is -30C in January.