As the winter wars begin, there's more questions as to who the Nobles are. Initially there were five noble clans, three of which have been revealed (Byakuya, Soifon (it's actually Yoruichi) and the Shiba clans). This leaves two more families to be determined.
Personally I believe that Urahara Kisuke is one of the families. The importance to his role throughout the series is unquestionable. He is the only one who can allow people to travel to hueco mundo, allows Ichigo to go to Soul Society, and is known to have been a Gotei 13 captain. With the latest chapters, it just strengthens this point. He is entrusted with preparing a battlefield for the Gotei 13, and is asked to do so by Yamamoto.
The fifth family to me would have to be related to Kurosaki. I believe his mother is part of the family, and that his father Kurosaki Isshin ran away with her to the real world, where they could've been helped by Urahara. But I can see Ichigo having a royal bloodline.
What do you think? If i messed up on any fact, please correct me.