[ArtTimeInvestor]

The way I understand it:

Introducing quantum resistant addresses is possible via a soft-fork, so rather easy.

Work on it already started: https://github.com/jlopp/bips/blob/quantum_migration/bip-pos...

If capable quantum computers become more probable and the soft fork is not already happening, it will be accelerated. And then everybody will move their coins to quantum resistant addresses.

So it does not look like a major problem. It will lower the price a bit though. Because old, lost coins will be revived and come to the market.

There will also be some type of war around "code is law" because some people will suggest to invalidate old coins on non-quantum-resistant addresses. That will be interesting to watch.