Aizen will become a hollow. See, I believe that the Hogyoku will transform him (accidentally, in a very un-Aizen-like manner). Aizen will become a hollow, and his Inner Hollow will drive him crazy. The Inner Hollows all possess people's instincts.
Aizen: calm and collected
H. Aizen: sadistic and insane
Aizen: plans his moves
H. Aizen: does the first thing that comes to mind
Aizen: calm and collected
H. Aizen: sadistic and insane
Aizen: plans his moves
H. Aizen: does the first thing that comes to mind