Looking at past bleach archs, the first arch tends to be a lead up to a second arch. In saying that, I think this war is a set up for a war between Soul Society and the Soul King. I do not think that Uryuu will stay with Juha Bach permanently, actually I doubt hes there to truly be with them. Remember, Juha Bach killed almost all of his family, and I think his mom included (his dad is still alive, however this isn't mentioned in the recent chapter for some reason.) Remember what was also recently mentioned, the reason Juha Bach announced that Uryuu was to be his successor in the way that he did was so that Uryuu could not make any moves himself, he is forced to follow Juha Bachs lead (meaning they are also aware of the possibility that he maybe unloyal to them.)
I do feel that Uryuu will kill end up killing Mayuri Kurotsuchi before all is said and done however.