The Current PoW design is an evolutionary dead end.
It only has few possible outcomes.
1. Price per coin fails to keep up with input costs required to run the network, in which case the Bitcoin Network Miners cease mining as no profit in it.
Bitcoin Network then seizes up in a death spiral.
2. Price per coin continues to rise as the insane energy waste continues, thus causing all ASIC miners to require Government Permits due to their energy requirements.
At this point , the Governments decide who may be miners, and requires them to block transactions per their government policies.
(Miners can't steal your coins, but can make certain that you are unable to spend them.) Not long after all of the Miners are Government Mandated, their will be a global collusion of what % each approved mining will mine
and then it is just another government controlled service and the energy usage will be managed at a sustainable rate, by mandating the hash and energy allowed.
Miners will only be able to make changes/upgrades when government policy allows. But since hash % will be fixed, energy waste will be removed as a issue and
there will no longer be a yearly need for new asics, as their will be no competition , but mandated mining only.
3. Price per coin continues to rise as the insane energy waste continue, but the energy companies refuse to allow permits for the miners ,
and outlaw Bitcoin mining in every country that mining would be profitable, therefore destroying profitability and ensuring the network dies in a death spiral.
The Beginning of this scenario , will be when they start showing ads of old people suffering in the cold and heat unable to afford their electric bill ,
because the evil corrupt /greedy bitcoin miners have driven up the energy costs for everyone.
So 1 & 3 are the death of bitcoin with the price hitting zero
and 2 it becomes a government servant with the miners doing as they are told for a limited/fixed profit margin.
Only an alternative consensus method can evade those 3 scenarios, and being energy efficient is a requirement to evade them.