This is not possible because public keys you want to crack are in hashed form RIPE-160(SHA256(public_key)). Grover's search algorithm can help with it, but speedup is much less, than with Shor's algorithm and won't be of much help with sha256.
However, if you wanted to break the hashed private key, you don't need to solve 256 bits. Grover's algorithm is a search, thus difficulty scales with the final hash key length, not the intermediate hashes. Still, it's only a quadratic speed-up and 160 bits is still pretty tough. But that's fine, as you can still intercept the public keys before they're hashed on the blockchain.