Kishi wont let kakashi and Minato fight with Madara at least until madara gets his eyes back.Ftg and kamui is too op for any living ninja who is not juubitr kishi must make madara 10 times stronger because it is impossible for him to take tobirama minato and kakashi together.A lot of plot twist will come in the next chapters:Omg:
Madara will foddersize everyone.
If Amaterasu is like the gravel under his feet to him , then Kamui isn't any good either to him.
Kamui can't affect Madara , because of his immense chakra.
and ftg , i think that Madara can foresee that , plus , the black zetsu is part of madara and since the other half of the black zetsu is the in the other side , that isn't covered (of obito's body) that means , that your theory is wrong. They will fight madara , because Madara is imortal he is the true imortal being in the series.