I'm skeptical that B is fully possible. You can create a PQ fork of bitcoin but you cannot automatically bring vulnerable wallets along - and there are a lot of vulnerable wallets, especially from the early days. There's a catastrophe ahead for bitcoin with an apparent probability of 1.0. That's hard to account for in this scheme.

Are you including these?:

Chance the computing is quantum and real but it doesn't scale in a way it outperforms traditional computers at any number of qubits, ever.

Chance the "good" quantum computing turns out to be as fake as the currently deemed fake quantum computing?

I would argue that the hackers will do the jobs of transferring funds from insecure wallets to secure ones very efficiently.