What would it take to get you to change your mind about PoW alternatives? How many years of secure operation? How much value transfer? How large of an ecosystem? How much academic research into the mechanisms?

Assume for the sake of argument that an alternative to Nakamoto Consensus is developed that meets your standards for security/decentralization and requires orders of magnitude less energy. Perhaps you're right and no such system exists today, but I'm not ready to accept that such a thing is physically impossible. Would you support hardforking Bitcoin to use the new system?

My concern is that miners never will, no matter the merits of switching.