I do not want to attribute to you a claim that you have not explicitly made, but you seem to be suggesting that, because of the difficulty, current performance does not rule out the possibility that CNNs alone might eventually be able to perform as well as humans (in terms of things like using existing knowledge to speed the assimilation of new knowledge, including new knowledge in new categories.) Maybe so, but that very much remains to be demonstrated (and the burden of doing so would rest with anyone who wants to make the claim.) Meanwhile, Hinton cannot be faulted for attempting to improve on the process.