I would tamper your quantum worries until they demonstrate they can factor numbers considerably bigger than 15....
FYI, "factoring 15" was about factoring a specific kind of composite number, the smallest whole of which is decimal fifteen. IIRC there are multiple composites that could be used as RSA moduli that were simultaneously factored by the researchers, and the interesting / worrying challenge is the question of determining whether some arbitrary RSA modulus belongs to that kind of composite, and after confirming that, interconverting from binary to quantum becomes a negligible cost.
FYI, "factoring 15" was about factoring a specific kind of composite number, the smallest whole of which is decimal fifteen. IIRC there are multiple composites that could be used as RSA moduli that were simultaneously factored by the researchers, and the interesting / worrying challenge is the question of determining whether some arbitrary RSA modulus belongs to that kind of composite, and after confirming that, interconverting from binary to quantum becomes a negligible cost.