Kishi could have just gotten rid of them with the infinite tsukuyomi. He could've have said as long as a person's being is present on the earth that it can get caught in the genjutsu.(they have their souls) Or with Orochimaru being caught in it could have disrupted the jutsu. Is Kishi gonna have Hiruzen and Tobirama get soloed in order to help prove Kaguya's power? Will it be a full team like when they faced jubito? Or is there still more that they are capable of?