Yeah but the Zanpaktou's reflect the user's personality somewhat don't they? You wouldn't imagine Kenpachi with Rukia's dancing shikai now would you...

Besides I think the last panel if a major clue that Aizen isn't dead. He is disintigrating but his head is intact and the hyogokyu is still exactly in the same place despite Aizen's chest vanishing.

I think they are going to pull out some crap like Aizen's being is now integrated with the hyogokyu and can't be destroyed unless the hyogokyu is destroyed. The Aizen you see is just a physical manifestation for people to comprehend. That way it will bring back Uruhara and co, as they surely are not finished at just pulling out their shikai's.., infact Ichigo's dad has not even pulled out his shikai yet has he?

Edit: Aizen's legendary mullet is also still intact, so he is definitely not dead.