The paths of the story are now starting to join
Sasuke+Itachi against Kabuto.
Edo Madara against the Kages.
Bee+Naruto against Tobi.
This will take around 15-20 more chapters to conclude. After the war ends we will have to see the outcome of it.
This will bring a last "good vs evil" Juubi vs Naruto and Sasuke?
Ramen guy vs Juubi? Who knows.. only kishi. 15 to 30 more chaps.
After this we could have a last fight between Naruto and Sasuke, depending on what happens in the war. 10 to 20 chaps,
And then we should see the manga rounding up with some more chapters, not much.
So i think that we will enjoy of 50 to 70 more chapters.
Perhaps more, depending if Kishi finds a way to continue with the plot, and this one not loosing any coherence.
Would be nice if kishi made more side stories like Kakashis, i heard he wanted to do one about Minato, though i dont know if this is for real or not. A madara vs hashirama would be awesome also. And Hiruzen in his prime would totaly rock. All the things that itachi could have done during his Akatsuki years. So many things that can be done.