I think this theory has legs.

Another train of thought on this is that if Harry didn't save Molly it is likely the WG would have had Michael in Chicago not in a position to help the WC.  Would also probably mean Michael couldn't help Harry on Demonreach.  I think there were some communications between Uriel and the Gate Keeper. 

I am not sure there is a black council so much as some angry entities that are looking to take their places back.  Dragons, Black Court, elder gods, etc.  I think that I should probably look over the guest list at Bianca's again as I think there were some serious bad guys in attendance.  I don't think Bianca was really much of a player but I think she was one of their pawns.  I would guess that the White King was among the alliance of evil until Harry defanged him.