pretty much every significant character is fighting to the death right now. when one side loses, what else will be left for Bleach to go on with?

I guess one side could retreat, but that would only delay the same thing from happening again, which would be boring.

I can't imagine what else they could come up with after this little war is over.

maybe Aizen is just a pawn being used by the 100 elite hollows, with #100 being 10x as strong as aizen. ichigo will develop about 14 more stages of release to rescue his kidnapped sister from them.