Hi guyz! With the recent happenings in the manga (particularly chapter 596), I have some doubts on what might happen next, since it would be too obvious if Ichigo fights against Ywhach and the Gotei 13 defeats the Sternritter. Here's what I think would happen:
1. Liltotto's Glutton ability would possess another ability that allows her to steal the abilities of anyone that she devours. I'm guessin' that she'll eat PePe and turn into this love-monster hybrid that the remaining captains would have a difficult time to deal with.
2. Renji and Rukia would have a difficult time in dealing with Bazz-B
3. Sternritters C, M, N, W and X are still unknown, so I highly doubt that they would play an important role in the war.
4. I highly doubt that Ywhach has a connection with the Soul King. Perhaps Ywhach was the Soul King's offspring with an unknown woman (say Rangiku's mother. Kubo after all, said that Rangiku's past would play an important role in this arc), but he decided to abandon the child instead.
5. I've heard a lot of theories that the Soul King is a being made of pure reishi. Perhaps it's Ywhach's plan to absorb the soul king's reishi in order to strengthen his own. He'll then use Uryu as a vessel for his newly acquired power (another fan theory)
6. Grimmjow, the Visoreds and the Fullbringers would become the war's reinforcements should Sternritters C, M, N, W and X appear.
I really hope Kubo has a lot of tricks remaining in that lil' ole hat of his.