Whether you like it or not, Pein and Madara are the final boss in Naruto. Mainly Pein since the protagonist will have to face him. If you havent noticed yet, Pein has been shown since before the timeskip. He wasnt showed fully because Kishimoto wanted us to all not know yet who he was. They dont make characters hidden like that for no reason unless its for something important, also, like Tobi's identity. Well anyways, Pein is the last boss, correct? We also know that Pein has the Rinnegan.
Look here at the Rinnegan.
Now look here. This was made in 1987, its called Calvin and Hobbes.
Thats not all. Lets dig in deeper.
Now check back at the 7th and 3rd panels of the Calvin and Hobbes sunday strip.
"CALVIN, THE MIGHTY GOD, CREATES THE UNIVERSE WITH PURE WILL!"
"THE GREAT CALVIN IGNORES THEIR PLEAS FOR MERCY AND THE DOOMED WRITHE IN AGONY!"
This explains exactly with Jirayas statement about the Rinnegan and the beginning and end of creation.
The 4th panel says the Rinnegan can even create life.
"FROM UTTER NOTHINGNESS COMES SWIRLING FORM! LIFE BEGINS WHERE ONCE WAS VOID!"
Now do you remember pein's cloning technique he did to make copies of Team Gai?
Wait, theres more....
Remember Peins Shouten no Jutsu?
They both wanted sacrifices.
The Rinnegan user, was from Calvin (the God). Now look at the last panel of the Sunday strip:
I hate using evidence that has to do with "similarities" but hey, wasnt the yondaime and naruto father son theory correct? Well look at the similarity between peins head and Calvins head.
With all this, now we know how the manga will end.
What are you going to do? Use sharingan to copy moves? Use Sharingan to evade? Use sharingan to......no you gonna die. End of Sasuke. With Sasuke being extinct, the world becomes a better place and everyone lives happily ever after.