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.
It would still tank the price. Right now many Bitcoins are lost because no one holds the keys any more. When they can hack it, suddenly the sell pressure significantly goes up.
