A change to what better POW? And risk disabling the current mining hardware? That would break the very foundation/fundamental structure on why everything in Bitcoin works.
Let me put it another way. If SHA256 suddenly became weak to collisions from some super-duper-quantum computers,
that isn't going to happen but IF, what should we do to protect our savings? Leave the fate decide for us or agree upon an algorithm change?
(in this case SHA512 that is 2256 harder to find a collision)I don’t have that answer for you, and Bitcoin should the least of the world’s problems if super-duper-quantum computers came attacking everything. But please understand what the argument is, based on how everything is working in Bitcoin.
The above example isn't a great one, since SHA256 is very strong and I doubt if I'll see a collision 'til I pass away, I'm just talking hypothetically. It'd also make the current mining hardware useless, since they perform SHA256d, but it'd be a consensus dead end with two choices. We'd either upgrade Bitcoin or make bitcoins useless.
Then it would technically be “the end” of Bitcoin, if the Core developers can’t find a solution.