I loved 552 but honestly, it just leaves you wanting 553 that much more. I want to see what happens when Itachi and Kabuto square off! I think Itachi is a supreme shinobi with skills that far exceed those of Kabuto; however, Kabuto's trump card beckons to tell a different story. That said who the heck is in that coffin? Maybe Minato, as it was mentioned earlier that he has been appearing a lot recently in the story (which he has), and would be a top candidate for an epic battle with Naruto. However in the episode where Kabuto reveals Edo-Tensei's secrets, he and Madara both agree it is impossible to resurrect any of the previous Hokage's (Konoha Kage's). Maybe it will be Izuna, Madaras younger brother. Or either of the sons of the Sage of Six Paths, who founded the Uchiha and Senju clans. Or lastly, dare I say... The Sage of Six Paths himself, which I personally feel is the only person who can give Madara that bone chilling look he had. The other reason why I believe it may be him, Is because Madara implanted the Rinnegan, for reasons unknown at this point. (Besides the obvious, i.e. to use its ocular power in battle, to control the ten-tail Jubi, and to have 2 of the 3 Great Dōjutsu-sharingan-rinnegan). Guess we will see!