So. Gin's stabbed Aizen. From the looks of things, there are three ways it can go down.
1) Short Term Shounen
2) Long Term Shounen
1) Short Term Shounen is the most likely outcome. In this, Aizen kills Gin, heals his wound, at least partially, then has an epic battle with Ichigo later. Yay.
2) long Term Shounen is much more interesting. In this, Gin kills Aizen, and becomes the new villain. He relys less on power and more on craftiness, so Bleach begins to instil a little of Psyren to its mindless battles. Alternatively, he's working for a new big bad, and Tite can carry Bleach on for several hundred chapters more.
3) Now this is where it get's good. In this one, it turns out that Aizen was a good guy all along.
Allow me to elaborate. My mate and I were discussing this, and I mentioned that originally, Kubo wanted a shadowy villain that operated secretly, with Gin as his sidekick. However, his editor advised him to bring back Aizen and have him turn out to be evil.
So how's this for a double subversion: Aizen's really a good guy, but using a Zero Approval Gambit: manipulating events so everybody hates him in order to achieve his ends.
So, in this situation, there really is a super-powered evil monster operating in the Shadows that only Aizen and Gin knows about. Aizen knows that no-one will believe him, but he also knew that by stealing the hohyoku and having everyone in soul society try to kill him, he might become strong enough to kill it. However, as a back-up, he also manipulated Ichigo to replace him if he fails. This explains why he's toying with Ichigo's friends: he doesn't want any innocents to die, including those from Soul Society. He just wants everyone to hate him, and to be out of the way when he uses the Kings Key to fight this monster.
This also explains why he destroyed the cleaner thingy, making a hyperbolic time chamber for Ichigo to train under. The stronger Ichigo gets, the better.
He expected Gin to betray him at one point, Gin being an agent of the Big Bad, but he didn't expect Gin to do it as effectively as he did. He was hoping to at least to weaken the big bad for Ichigo, if not kill it himself.
Admit it. If it turns out that Aizen was pulling a Thanatos Gambit all this time, all would be forgiven.