If a new consensus method came along that was undeniably more efficient would bitcoin be able to come together enough to agree and make the change across the entire network?
It is technically possible to change the consensus, if the majority of people wanted it to - this is not like some 50% or more decision mind you, because that could potentially split the network in half.
But actually, the overwhelming majority of BTC users do not want to see any change from Proof of Work, as you can see in my and other users' personal text (as of Jan 2023).