So now what- even post quantum cryptography isn't good enough?

Wasn't too long ago Vitalik hardly considered quantum computing a threat.

Now he's questioning if even post quantum cryptography could be at risk.

Though he notes we will need some form of post quantum cryptography:

"However, signatures and encryption serve different purposes. Buterin argued that public-key encryption presents a harder challenge because it needs mathematical structure beyond hashes alone."

My take is you need a solution to get off ecdsa / rsa yesterday because these were already at risk with "human" math.

And you need crypto agility in case AI math solves post quantum cryptography.