I think that some may be underestimating Naruto and Konoha.
Pa frog mentioned Naruto learned both Frog-fu and Sage techniques (i.e. jutsus), the latter of which (some new jutsus) we haven't seen. Don't forget Naruto has been practicing some secret jutsu, no one knows about, and we've all speculated about. He may come back in the same outfit, but he's going to be on a whole other level than before. I'm not sure how he compares to Jiraiya in Sage mode, but he seems to be better than him in all phases of that training. We don't know how much better Naruto is or how much that elevates his ability. Naruto does not have Jiraiya's experience, and I'm not giving him that, but Naruto learns pretty quickly and adapts well in battle. He's also going to have at least Ma and Pa frogs' battle experience in general and specifically against Pein. The also extend Naruto's abilities, and I don't think we've seen all of their jutsu either. Pein won't fall for the same song Genjutsu, so I figure that there will be new jutsu shown.
Pein and his invasion:
While Pein may not be killed in his assault, he's not going to capture Naruto either. The only person of caliber who has responded to Pein thus far is Kakashi. The next chapters are going to show Pein's assault, and Konan's appearance. I wouldn't be surprised if one objective of Pein is to retrieve that body of his that was taken by Jiraiya. Unless Pein defeats everyone, not all 6 bodies will fight against Naruto at once, like what happened with Jiraiya. I think Konan fights Tsunade (who was on her way to fight Pein when Konan will intervene).
I wouldn't worry about Sasuke or Madara showing up, there is still the 8 tails to deal with, and I thought they would be busy sealing him. However, Madara is going to be busy smacking the crap out of Sasuke for blowing it after Madara pledged for him to everyone else in Akatski.
I hope after this series ends, Kishi creates a new one. Naruto battle royale, where we get to see the fights we missed. For example, Jiraiya and Itachi. Just an afterthought.