Before I get into the weeds with links ITT, to be clear, if QC does reach a hypothetical power that would threaten private key security, a BTC fork seems to be the general consensus for the main possible fix.
yes, that is how cryptography has been its entire lifetime. ever since it was perceived more than 2 thousand years ago (before computers), every cryptography method had an expiration date when they become obsolete and are replaced by newer ones that are stronger before the same thing happens to them too.
as for ECC and SHA256 (the two main cryptography used in bitcoin), i don't think they would become obsolete anytime soon but when they do, Bitcoin simply upgrades to newer and stronger algorithms.
Not disagreeing with what you said but it's not like BTC has undergone that many forks of its own volition...ie. a fork for the health and progress of its own network driven by its community/devs.