I don’t understand why people assume Bitcoin is the first and only target for a future quantum computer. Every other system on earth will be rekt first, won’t they?
Discussion
Most of the world has been working hard on this for years.
Major banks are already 6 or 7 years along the migration path.
All the major browsers are at least hybrid-PCQ, same for Google drive and all such things.
Signal is pretty much fully migrated to PQC already. imessage too.
Latest versions of MacOS and iOS are quantum-secure TLS
List goes on.