Lemme find the copypasta...
Official list of Bleach characters who will serve as the villain
Note: Each one will extend the manga another 150+ chapters.
-Old man Yamamoto, after Aizen does something to make him look evil
-Ichigo after he can no longer suppress his Hollow (probably not gonna happen, but we can hope)
-Urahara after revealing he manipulated Aizen the entire time
-Yoruichi, Vizards, Isshin, and Arrowdad all working under Urahara
-Delicious flat chested lesbian follows Yoruichi
-"The King" or whoever Aizen is trying to kill, and his organized team of minions
-Whatever inhabits Hell (Kubo said he's gonna do an arc in Hell)