Re: Aizen is back.
I'm going to ignore the current argument and get this back on track :D
I hope Aizen becomes more involved in the storyline. He is, in effect, a god and in the next chapter (hopefully) we should be seeing him walking out of his prison with some inclination as to what he is going to do next. Was the Sternritter part of his plan? did he see the invasion coming? did he plan the invasion himself? all I know is the super Genius Aizen is normally at the heart of these kinds of things.
I'm less bothered by the notion of him being immortal or not (In my oppinion he is) but I'm more intrigued by his Zanpakuto. When he started evolving he didn't use it's powers, he just went for pure power as he didn't seem to need Kyoka Suigetsu. We also saw his arm fuse with his sword, does this mean he has also fused with his Zanpakuto? if he has then he really is going to be god-level.
And finally, as we have come to expect from Aizen. What if he isn't in that prison, maybe it's an illusion, maybe the Sternritter is an illusion. You know what he can be like!