naruto already used up so much of his chakra fighting the hokage, raikage, resurected raikage, madara,white zetsus, etc. & now has to face tobi. . . If sasuke was to pop up on the scene. . then chances are, naruto is SCREWED. . & seeing now that powerful sharingan holders can posess renengan. . hopefulle sasuke dont get that shit. . because that would be cliche. . where the hell is sasuke anyway ?? whose going to stop kabuto & these damn resurections? WE NEED ANSWERSS!
I think,Sasuke could activate the rinnegan
too,since he has EMS now.Maybe,in order to
activate the rinnegan,they need EMS activated and
some other factor,which is,maybe,battling with
your important rival from senju or uzumaki