You could look at only two niche blockchains, QRL and ABEL, and they are both affected. Algorand is the most established L1 with a quite developed migration plan (https://algorand.co/technology/post-quantum) but also not really thriving. I think for Bitcoin in the longterm it is a massive risk psychologically, because what to do with all of the locked in value, that cannot be migrated. My guess is that the market panics and security breaks down, because it is not worth it anymore to run that many nodes. Best time to buy would be then and hope it recovers. It is actually a big chance to move just to another L1 which migrates. Those risks are all priced in.