This. And also that if Nimaiya knows all the swords' bankai, and later caught wind of a [theoretical] fake one Aizen concocted to show the gotei 13 as his captain's application, then Nimaiya sat on his ass and did nothing with that information for decades until it was too late.
But yeah, you're right Abandon, that's the reason that Ichigo became their last hope; but like Serra said, that was only after he revealed complete hypnosis to gotei. His captain's app. demonstration must have taken place years and years ago, but obviously sometime after he performed the visored experiment since he was still a lieutenant at that time still.