One thing that crossed in my mind when I was in the shower(showertoughts, heh) was that I was recalling back the times when Haschwalth called Uryu his successor, and when Bach renamed him his successor, and I could not help to think that despite what everyone seems to be thinking right now, what if Bach actually WANTS to become a comatose soul king, so that he can have an infinite supply of souls and does not need to wage wars anymore? This would mean that Uryu would then become the leader of Wandenreich.
However, I had trouble fitting this theory becuase in my mind, that somehow would mean that Uryu would have to gain the ability of Bach somehow, wich I doubt is going to happen. Do you think Uruy would just lead the Wandenreich? If he was officially made the leader there, I think he would just disband the whole group.
Maybe Bach wants to become the comatose Soul King, but wants to first take on his enemies. This would perhaps make most sense for the story since if he goes comatose, he could be easily killed, and that would also mean that we would not be getting any fights, wich isn't very likely going to happen. So, all that is left now is to eliminate Ichigo & his Group and that will ensure that Bach almost certainly cannot be touched again.
This would also tie in with Bach's words when he said when they were going to the Soul King Palace that "You know it will be for forever, right?" indicating that he will stay with the royal guard there, guarding Bach for millennia.
I think it's possible that now that Soul King is dead, Bach will be forced to take the role of the Soul King since Soul King is now dead, to prevent the worlds from colliding. And Bach is probably happy to do so, because he stated that he doesn't like wards, so the continous stream of souls that he'll get as a soul king, will probably be enough to sustain him and prevent him from degenerating into his original form.