You guys are underestimating Madara too much. Keep in mind that he has the rinnegan, and unlimited chakra. He's only playing with the kages. He could make 1000 clones if he so wished without tiring out. How the hell is Kakashi supposed to simply use kamui? There would still be the clones, and then they could use reverse summoning to bring Madara back. Theoretically, the clones could stay there without disappearing even if Madara were trapped in the other dimension because he's dead and does not require any nutrition or the like, and again, unlimited chakra. Kakashi can't tackle 1000 Madara clones. The kage can barely keep up with 1 per person.
I think you forgot about Naruto, Bee, and Guy.
Chakra-wise Naruto and Bee can match Madara. Kakashi can analyze from the rear with Guy as his back-up.
BM Bee and Naruto can hold the point of attack effectively, with Naruto clones matching Madara clones. While the real ones fight against PS.
Shinra Tensei isn't a plausible option, along with several of the paths. Quite frankly, Madara hasn't shown much ability outside of the push/pull factor of the Rinnegan. The 2 strongest Tailed Beasts can hold there own, in fact, I'd say they keep him on the defensive enough to give Kakashi the opening he needs.
It doesn't need to be a big window, since he's been shown to be very fast and very accurate with Kamui as of right now.