User blog comment:Lia Schiffer/390: Beyond The Death Understanding/@comment-1690831-20100130172125

I think that Ryuken should appear to fight Aizen also. Sure he's only a human, but look at how strong Ishida and Chad got in such a short time. He also seems to be just as important to the plot as Isshin and Urahara imo.

Also I think that the short arc is going to be another flashback arc explaining all of Isshins past and probobly more about the spirit king. Then the much longer arc would be just everyone training again, including the Captains and Lieutenants this time. As to why Aizen would be waiting so long to attack again, aside from the fact that he's basically lost his entire army, I think Orihime will end up destroying the Hogyoku by the end of this current arc. She said she was going to about 150 chapters ago, and I doubt that Kubo would just forget about that.(though I have no idea as to how she'll actually accomplish this)