That's true, but given that Madara can avoid bodily damage by using his Mangekyo, and that Kabuto might as well be the Jesus of Naruto I don't think Sasuke is going to make progress in killing either of them. He really has nowhere else to go when Madara turns him down.
That, and should the Ten-Tails happen, he might as well fight it alone, w/out the Nine or Eight Tails, Bee and Naruto are pretty wimpy, save Sage Mode for Naruto.
It Could be Hashimara Senju in the final Coffin the First Hokage who pwnd Madara, but idk.
Xer0 \^/