Board Thread:Naruto Discussions/@comment-24514198-20140604211103/@comment-24891350-20140608040908

Madara was the mastermind behind the Akatsuki and Obito and everything that happened so he was fit to e the final villain.

However if it turns out that Kaguya was somehow controlling Madara and was responsible for his plan then she has the right to be the final villain.