If Ichigo killing Aizen = end of bleach....that's gonna be a lame end.
Plus Aizen is more an enemy of the old shinigamis then he is the enemy of Ichigo. Ichigo is sticking his nose into it.
Maybe the end of bleach should be Ichigo dying?
Edit: Just remembered the thing about Aizen wanting to obliterate Ichigo's hometown.
But meh Aizen will most likely fail. But hmm it would be awesome if Aizen does succeed by destroying Ichigo's hometown then he goes to the King and kills him....then Ichigo fights Aizen to the death and they both die? I just love endings where the hero dies....
On topic: Byakuya's pride is annoying. It'd be cool if Ichigo kills him in the arc. I'd love to see how Ichigo and Rukia's relationship will deal with that.