Naruto now has reached chapter 533, in the chapter is ongoing battle between Asuma Sarutobi and his pupil, Ino-Shika-Cho (Ino Yamanaka, Shikamaru Nara, and Choji Akimichi). Until chapter 533, Kabuto has raised many legendary ninja that have died such as Hanzo, Seven legendary swordsman of the Hidden Mist Village, Akatsuki members, Asuma Sarutobi, Chiyo, Hizashi Hyuga (Father of Neji Hyuga), former Kage, and other legendary shinobi.
But my questions, where is Sakumo Hatake?, The Konoha White Fang (father of Kakashi Hatake), I did not see Kabuto summon him. Whether Sakumo Hatake is the person in the mysterious coffin? I don't know for sure, but how about your theory regarding Sakumo Hatake and the mysterious coffin?