Addresses that have been sent from will be vulnerable because their public key will be displayed in the outgoing transaction. One-use addresses will not be vulnerable, as their public keys are indeed stored only as hashes in the blockchain, but the algorithm is not only RIPE, but something like SHA256(RIPEMD-160(SHA256(Public_Key))). I dont know about RIPE, but sha256 should be QC resistant. Thus if you do not reuse addresses you should be safe against QC.