There are 4 ways the author could have Aizen resolve the situation.
1. Gin steps in. This can be combined with any of the others, but it would be a nice way to show that while Aizen may be strong, he does need help and that the captains' attack on him did actually matter and threaten him.
2. Is actually injured, but goes hollow form to regenerate. Not that that plot device is used much anymore, but technically the arrancar do gain a large amount of spontaneous regeneration upon sheathing their sword. It would be nice to see the author use a mechanic he introduced before and not having completely forgotten about it. Least likely scenario.
3. It was all an illusion. Aizen was munching on some fish n chips about 5 feet to the left. He reveals that he has them all under his complete control and thus it is time for the story to revolve around Ichigo again. Fairly likely
4. He just too darn strong! The worst outcome. Nothing anyone does to him matters. He didn't need regeneration, an illusion, or anything else. His reiatsu and skill are just so far beyond everyone else that they don't matter. HE shrugs it off and eventually Ichigo has to fight him.
The third one is indeed the most likely, especially given what Unohana said to Ichigo about him being the only one not under the illusion powers of Aizen.
I don't know what Gin is supposed to do, I don't even know why he's still alive, he's nowhere near as powerful as Aizen and has already taken out one of the Vaizards, a bit odd there was no retaliation for that. (chapter 377 I believe)