It is partly true even if not entirely impossible, let's say that there is not enough computing efficiency to be able to satisfy the request but this is only applicable to the present, because in truth in a very near future (20 years are estimated but perhaps less ) quantum super computers will be able to crack a sha256 encryption very easily and it is not science fiction but the truth. So if governments fund enough developments for this technology, a team will be needed to run for cover to implement an additional level of security but obviously someone is also funding the defense side. I have learned though that right now Attack development is slightly ahead (maybe a couple of years) and this could be catastrophic if that happens.