Precisely - quantum computing is not just a threat to bitcoin, but a threat to all kinds of passwords, encryption, etc., used all over the internet. It's not just going to be a case of suddenly one day everything on the internet is insecure, with criminals stealing bitcoin, stealing fiat, hacking accounts, intercepting emails and communications, and so on, with abandon. Quantum computing at a level which would be a risk to bitcoin is decades away.

As above, we have years or even decades to prepare for this. There is nothing stopping bitcoin for adopting quantum resistant signature schemes and forking to implement them. There is no inherent necessity to move to a different coin. And creating a private key using your fingerprint doesn't solve anything in terms of quantum resistance if you still use ECC to turn that private key in to a public key.

That's the whole point of mixing or coinjoining prior to depositing to an exchange - to break the link between the stolen coins and the attacker's exchange account. Or they could just cash out peer-to-peer and never touch a centralized exchange at all.