I'm willing to bet Suigetsu has something related to how to control or stop the Edo Tensei. It'd make things a lot more interesting. Itachi and Sasuke might kill Kabuto regardless of the fact that it won't stop the Edo - he might end up in the same gourd with Orochimaru, which would be fitting. At the very least, it would probably set the others free of Kabuto's control. I could see Itachi saying something about "I believe in Naruto... and you Sasuke," poking Sasuke in the forehead then disappearing in a bunch of dust, having completed his objective to protect Konoha and having seen his brother one last time.
It would also explain why Dan is still hanging around. If he were free of control, he could rush to the battlefield just in time to see Tsunade die, then float off in a dust mote, again having his soul fulfilled. More likely than not, Naruto will show up just in time for both of them to compare him to Tsunade's brother, and make him the Hokage, passing on their dreams to him. (I mean honestly! If Naruto's going to become Hokage, could there be a better way?)
That leaves Sasuke and Naruto to face off and then deal with Madara and Tobi. Sasuke might try to control Madara, or Naruto might just show up and squish him. I'm not sure exactly how the final meeting between those two will go. Either way, Madara will go down before Tobi. I could see Madara smiling as he dies, saying something about how "It was good to be able to fight with somebody strong again... He reminded me of you..." [insert picture of Hashirama smiling] Cut to dust.
