Ichigo i think comes from a lost and forgotten royal family or somthing like that. Also Zangetsu seems to be inherited by Ichigo. His father also has a getsuga tenshou and is one the most illusive characters. Keeping all that in mind, Yamamoto has been the strongest shinigami in over 1000 years and is on the verge of "retirement". Who is qualified to take his place?
What about Ishida? By avoiding going to hueco mundo does this mean he is a part of the quincy revolution? He obviously knows something.