Burying the head in the sand doesn't work. Quantum-safe algorithm candidates exist. Post-quantum cryptography is a bonafide field with families of algorithms that exist, e.g. lattice/hash/code/multivariate based. If a user has to choose between two cryptocurrencies, one of which is quantum safe and the other isn't, the user will choose the one that is. The ultimate choice of algorithm doesn't have to be finalized right now; that will remain a work in progress for decades, but getting there is not a one-hop journey.

For comparison, XRP already has a roadmap: https://cryptonews.com/news/ripple-post-quantum-readiness-xr...

Because XRP is not decentralized, it will be easy to upgrade. With bitcoin, you have to convinve the node runners to upgrade - which means the taken patchset must be sound and verified in depth beforehand.