Quantum will likely be able to break classical encryption within a defined period of time.

If you have an encrypted message, it can see the encrypted text and attempt to break it using a probability curve with a language model to identify outcome.

But when it comes to Bitcoin, or any keypair, the private key cannot be derived from the public key, so you need a different target to focus on.

Bitcoin’s defence isn’t just cryptography. It’s probabilistic obscurity.

What are you going after?

Wallet addresses with valid (high balances)?

Random, valid addresses?

The problem is not how easily will they break encryption, it’s how will they target which encrypted wallets to break?

Key rotation is going to become more important as we move towards the quantum singularity.

Quantum is useless without target selection.

Target selection requires information.

Bitcoin hides information by default until the precise moment of movement.

After that, key hygiene determines who gets hurt.

Quantum, however, is a threat to general encryption, much more than Bitcoin, which uses signing, not encryption.

And yes, Quantum will likely break this within the next fews years (but not for a while).

But because we know what Quantum does and more importantly, doesn’t do, we can change encryption (and key signing) to work in ways Quantum doesn’t threaten.

As for historically encrypted data and key signing. That is a different problem and the reason the NSA still capture all your encrypted data. They probably can’t break your encryption today, but they may be able to break todays encryption tomorrow.

But if we do it right, they won’t be able to break tomorrows encryption tomorrow.