It really seemed to me that Minato Sealed the Yin Kyuubi in himself first, BUT It seemed that Sandaime sealed Oro's Hands and Hashirama and Nidaieme the same way too.
It stands to reason if Kishi si consistent that the Kyuubi's Yin should have been released from inside Minato Just as Shodaime, Nidaime, and Oro's hands were released from inside Sarutobi
It's anybody's guess where the Manga goes from here on. So many potential key players. One question is why Kabuto never used this scroll to ET the Hokages. It seems unlikely that he would not have known about such a Major find in Oro's possesion.