User blog comment:Godisme/The Fire 2/@comment-3521993-20120908232743

What people don't realise is the nature of Yamamoto's Bankai. Notice the weakness that most Shinigami have: They cannot use their Bankai long. This is due to the expansion of Reiatsu. However, Yamamoto's and Ichigo's are compressed. This is my theory as to what the special war potentials are: Shinigami who can't have their Bankai stolen due to the fact that Reiatsu doesn't pour out of them every which way, like Yamamoto's flames disappearing into his sword. Really, there is no plot device to explain this: It's all in the mind of a Zanpakuto. Kenpachi on the other hand, is more to do with the fact that he doesn't have Bankai, and so cannot have his stolen. I highly doubt Aizen will be another, and there is no way that Uryu, Chad, Orihime, or some random person like Nel or Grimmjow are potentials. I have my mind focused on Kisuke and for some reason: Yoruichi.