Then naruto & pain fight should end in june
Maybe he'll be a chuunin then.
Other thoughts:
1.) I wonder how Naruto was able to form the Rasengan so quickly. I presume it's a combination of improved chakra control and nature chakra. The main thing that's been hindering his chakra control. If he's balancing his own chakra with nature chakra while the nine-tails chakra is minimal, then the kyuubi chakra should be interfering less.
2.) I think that Nagato has an immense amount of chakra to drive these bodies. He underestimated Naruto and Konoha, which means he's expended a lot of chakra already (along with his atom bomb jutsu). If the fight starts to turn sour Konan will likely take a depleted Nagato away (who we haven't seen yet) and the bodies will simply collapse or be collected. I don't see Konan stepping in to fight, she's not the fighting type in my opinion. Pein sent her into Konoha to gather information on Naruto, while he sent in some of his bodies to kill Konoha shinobi. That she killed to gather information is stipulated, but it was a means to and end and not her goal.
3.) This is not going to be the fight were Naruto talks about his loneliness with Nagato, that will be their final (in my opinion, the second one) when Pein is dying.
4.) It's been stated in the manga that after Orochimaru and the Sand attacked Konoha that they were vulnerable to war if other countries saw them doing fewer missions and top missions. If that's the case, war is inevitable, but I wonder if that's really in Akatsuki's best interests. Kabuto is the new Orochimaru, I don't know to what degree. I would think that after the Akatsuki arc, Kabuto will have arranged alliances to forge a war.
5.) What happens to Sasuke once Madara dies? He's always had someone to tell him what to do (father, Kakashi, Orochimaru, Madara) with a goal to kill somone. Sure there are the elders and Danzou, but once they're done he'll have nothing to do but revive his clan from one person, which is feasible genetically. It will introduce too many double recessives into his gene pool. If he changed his attitude and rejoined team 7. They would be invincible until Sasuke felt Naruto was too strong (wishful thinking.) In theory, he could gather up an army to storm Konoha while it's weak.