I understand it's very different and that it isn't likely to replace non-quantum computing in our lifetimes, if ever. It doesn't need to replace general computing to threaten public key crypto. It just needs to scale up in qubits and preferably remain stable. There's a lot of very smart people working only on this and with basically unlimited funding. What's commercially available is likely not even the bleeding edge, given the intelligence applications.

I'll agree that CRQC it's not absolutely inevitable. However, nobody can claim it's impossible either. It would be hard to even prove it doesn't already exist somewhere.

There's already relevant non-QC attacks against P2PKH. If they're not moving them to SegWit, they're already at risk. If a fork is propsed and they still don't move, that's on them. I would like to know how many coins/wallets are affected, if anyone can answer that.