If Naruto learns from the 8 tails how to control the kyuubi in the future, he would be unbeatable.
Imagine Senjutsu mixed with Kyuubi chakra.
This combination would be too dangerous - Rasen-Shuriken would equate or surpass pains Shinra Tensei Destruction.
I predict that naruto has already made a clone (animal pein laying on the ground) all he is waiting for is the 5 second interval when he forces deva pain to use his tech so that he can deal the final blow.
I believe that the animal pein on the ground is acually naruto's clone playing died and absorbing natures energy. sort of like chuunin exams in his bout with kiba. Naruto would have most likely have gotten the idea from here:
I think the battle might start with a sudden shock on the face of Hungry pein as his eye rolls back and falls to the ground. You see what seems to be animal pein behind him with another sneak attack Rasengan. Pein is puzzled but realizes the truth in a second and commends Naruto for such advance thinking tactics ... Bla, bla, bla (Dialogue)... "It's futile," "you can't win". Pein uses shin tensei to blow naruto away plus clone. and naruto is now out of senjutsu pein flips onto naruto back with a knee, who is now prostrating on the ground in tremendous agony and pain. Pein says I would be taking you now,... this a small taste of pain when you resist "god". Pein stabs Naruto's right hand. Pein say's now this should stop you from resisting any further. Naruto feels an inability to mold his drained spiritual energy source with his physical stamina to create his chakra (the rod is disturbing the molding of his chakra).
scene 2 Now in naruto's mind were he is standing in front of the Kyuubi's gate wondering if he should call for his help.
Next Chapter 436 - "Naruto's Decision: Life or Death