This is a great point in general: sometimes the problem isn't an adversary using knowledge in your field against you, it's the unintended consequences of progress / changes in adjacent fields.
It also underscores that, when dealing with things like passwords, it's helpful to be able to seamlessly upgrade to more robust methods down the line, e.g. "if this password hash was generated using the old method, check the login using that method but rehash and update the database using the new method after authentication."
