The specter of quantum computer systems is principally that they’d break Bitcoin’s elliptic curve cryptography, that means they may derive a personal key from a public key. There’s additionally the potential menace to mining, however I imagine that is far much less understood (it definitely is by me), so the next applies mainly to the elliptic curve cryptography.
The overall resolution to the quantum menace is to introduce a post-quantum (PQC) signature scheme, which might be completed with a delicate fork. Then, everybody must migrate their funds to the PQC scheme in time earlier than the quantum menace materialized.
The query then turns into what to do about cash (UTXOs) locked with susceptible public keys. One possibility is to do nothing and let the cash ultimately be stolen by quantum attackers. Another choice is to make these cash unspendable with a delicate fork after a set deadline. But another choice is to make these cash unspendable utilizing the susceptible signature scheme alone, and there are a lot of technique to go about that, however all of them might be completed with a delicate fork.
The one time we would wish a tough fork is that if we would first wish to make the susceptible cash fully unspendable with a delicate fork, after which later wished to re-enable spending with a safe signature scheme. Until the specter of quantum computing materialized abruptly and unexpectedly I do not suppose we would do this (and we’d have greater issues anyway).
