i realy dobut now that madara will be final vilian,as the spoiler goes it show that madara wasnt evil,he didnt took eyes from his brother but his brother gave him.Final fight will be
1)naruto vs pain,sasuke and the others will help him.But the fight will be with kyuubi's powers,
2)or naruto will fight sasuke,dont know yet why,but again with kyuubi's powers
dont know what of those 2 but one will defenetly fit in in the end...
or maybe naruto and sasuke will fight some other guys,who we dont know yet.
We forgot about kisame he will be maybe some imba vilian in the end....who knows
but i think that last fight will be NAARUTO VS PAIN.........Rinnengan vs Will OF fire....
and naruto will become hokage,but maybe he will die.....or sasuke will be in dieing and naruto will give his life for sasuke's