I still believe in Itachi and I'm not denying the fact that his current body is a artificial body, but that doesn't mean that Madara himself is gone. The one person that brought hatred into the village Konoha and the rest of the world,.. he corrupted so many lives:
1. His plan with his second Kyuubi attack was to mess things up between Konoha and the Uchiha clan, so he could get his revenge on his clan who turned their back on him by choosing Hashirama as their leader + his brother's sacrifice was for nothing in the end. ( and it seems like he didn't put a lot of effort in fighting Yondaime. I'm convinced that his second kyuubi attack was to mess things up between Konoha/Uchiha. )
2. With his second attack with the kyuubi, he fcked the life of Naruto and Sasuke.. both of them lost their family, they grew up by themself and both of them didn't know anything about their life + the big picture of the shinobi world. The political structure of ruling nations and the sacrifices that had too be made. Madara manipulated Nagato etc.
Madara's influences on the shinobi world started the moment when he got defeated by Hashirama at the Valley of The End. So it would be the most fitting badass villain for Naruto in the end. IF HE ISN'T MADARA, then let it be his little brother; Izuna. Acting like he's his big brother, trying to take revenge for his sacrifice that he made and for his brother's honour.
I would really be disappointed in Kishi, if it wasn't Madara or at least, Izuna. If it's gonna be a Uchiha shinobi related to blablabla, woooohh.. I would be so disappointed !
The perfect ending for me would be like:
Naruto and Sasuke co-op against Madara. Sasuke has to redeem himself and thats why he's gonna use a jutsu on Madara by sacrificing himself with the idea that Madara is gonna die with him. ( same thing what Majin Vegeta did against Fat Buu ).
Sasuke fails and dies... Naruto seeing Sasuke falling from above on the ground with blood all around his face, saying the last words:
Sasuke: Why that scary face, Naruto.. I was ignorant and jealous, a fool from the beginning for not admitting that that you're a true shinobi. Naruto, you've always been better and what a fool I am for hurting you guys so much.
Sakura: *screaming* SASUKE !!! She's running towards Sasuke. (Naruto just can't believe that Sasuke is dying, he's in shock)
Sakura: *holding Sasuke in her arms*; Everything is gonna be allright, Sasuke.. (tear drops falling on his face).
Sasuke: (coughing up blood from his mouth, staring into Sakura's eyes); How can you even shed those pure tears for a evil guy like me? How can you even look at me, when I wanted to hurt you, make you bleed for my own vengeance? You're a true angel that sacrificed everything for me, even now. Sakura, I always loved you, but the person that deserves your love more then me, is standing next you.
Sakura: *staring to Naruto, closing her eyes ans saying* The feeling that you've, that you don't deserve me, is the exact same thing what I think about Naruto. Naruto doesn't deserve me either. We are both broken and the only way for us to live in happiness, is being together for us and for the true savior of the shinobi world, Naruto.
Sasuke: *puts a smile on his face* touches Sakura face and saying; Thank you, Sakura.. then he stares at Naruto ( who's slowly getting crazy like a M.. fcker and not knowing how to react ) and says; you saved your friend like a true hero, like a true brother, like a true Hokage. Now start showing what a Hokage is made off,.. chance this cursed, hatred shinobi world once and for all. Spread your love and peace around the nations and mark yourself as the true Sage. Naruto, you know how much pride I have as an Uchiha, but I feel the need for bowing down in my last seconds on this world, to a true Hokage. You saved me from my pain, so it's time for saving the others. Good bye..
Naruto: Sasuke ? Sasuke? SASUKE !!!!!!!!!!! BAM BOOM --> Super Saiyan Kyuubi / Sage Mode 9
Sakura: Noo, don't... don't go, please, don't do this to me, sasuke? SASuke? SASUKE !! * She uses a more advanced jutsu what Chiyo used on Gaara for bringing him back from the dead. Sakura has to give Sasuke half of her life-span for saving him..
Uchiha Madara: God damn.. when does this love shit stops,.. OOh sasuke, noo Sasuke, don't sasuke !! Sasuke was a fool, simple as that. Am I the only one, who loves to spread hatred around here? Well,.. you've to be good in something, right Naruto??
Naruto: Madara, you're going down, you piece of shit !!
Uchiha Madara: that's it, let it all out Uzumaki Naruto !!! finally, a real showndown..