Danzou obviously a very bitter man having lost out to Sarutobi he seems like he'll be pursuing power at any cost using his puppet Sai who will no dought learn of his masters agenda and turn on him after being changed by Naruto's "mysterious power"
Sai ...now this is the man who is gonna be the interesting one enforcing Danzou's hidden agenda and i feel he will make a very interesting replacment for Sasuke if Kishimoto deals him the right cards.
I think Sasuke will end up killing him (or at least i hope so) and naruto having now become freinds with Sai will realise the freind he was looking to save no longer exists thus setting the scene for a final showdown between the 2 of them
Yamato seems a little bland in appearance i just hope his personality compensates but hes only just been intoduced and hasn't had much time to put forward his case so its hard to get a fix on him having seen so little but for what i have seen i find him i think hes going to be a very poor substitute for Kakashi[