There's no need for a third way, Satoshi's coins are already safe from quantum computer attacks.
Quantum computers can't calculate a Bitcoin private key from an unspent bitcoin wallet, so Satoshi's coins are safe from quantum computer attacks. He never moved any of his coins. If he had moved some he would have revealed a public key which a quantum computer needs to calculate the private key.
https://bitcoinmagazine.com/articles/satoshis-genius-unexpected-ways-in-which-bitcoin-dodged-some-cryptographic-bullet-1382996984Quantum computers are capable of breaking elliptic curve DSA (ie. given a public key, a quantum computer can very quickly find the private key), but they cannot similarly reverse hash algorithms (or rather, they can, but it would take one 280 computational steps to crack a Bitcoin address, which is still very much impractical). Thus, if your Bitcoin funds are stored in an address that you have not spent from (so the public key is unknown), they are safe against a quantum computer - at least until you try to spend them. There are theoretical ways to make Bitcoin fully quantum-safe, but the fact that an address is simply a hash of a public key does mean that once quantum computers do come out attackers will be able to do much less damage before we fully switch over.