What do you think will be the last Naruto Akatsuki antagonist of the series?
First, is Madara, who is the leader of Akatsuki. Then Pein ago, the guardian of the highest dojutsu descendant of the creator of the ninja world and taking into account recent hero has a bone to pick with him. The latter could be Zetsu. We have information both Madara and Pein background, but the character is surrounded my mystery. It is also considered Tobi treatment as a subordinate, even if it was later revealed that he is aware of his true identity.
I think Madara is the end of naruto akatsuki