Simple. By having a fork that is actually supported by the majority of the community. That means core must support it first, which makes the process kind of centralized.
Agreed, but that's generally speaking... Your statement is like saying 'Eth will be worth $400 when the community values it as that much", its an accurate statement but obvious.
Without trying to come across as malicious when do you think this is going to happen? Do you see any competitors in the near futute?
Also what if Bitcoin doesn't get 'wiped out' but offchain atomic swaps just dissolve it into a class of popular coins?