Am I right in thinking that (assuming enough miners agree) – it would be possible to change from SHA256 to some other algo – eg. SHA512 or something different entirely?
Wouldn't that also make all those special dedicated ASIC mining rigs useless as they are made for SHA256 only.
At the same time the electricity footprint for the bitcoin ecosystem would go way down – but since the difficulty can be adjusted – it will make no difference to usefulness/transactions.
TL;DR – if the hash algorithm changes for bitcoin – you would save a lot of electricity and piss off a bunch of miners who bought special hardware