Quote Originally Posted by Sidnne

Its Kishi's symbolic battle between Naruto and Sasuke that has been taking place since the beginning of the series, with the two of them trying out-do or at least match each other.
It began with the tranformation jutsu (at the academy), carried on into chakra control (running up the trees), continued to taijutsu (chuunin examine tournament), and now into the development of jutsus.

You can see it clearly when you look at the origins of the techniques.
First, Sasuke learned Chidori from Kakashi. Naruto then 1-up'd Sasuke with the Rasengan. Both were small, but powerful jutsus, which were contained with one hand and more or less a thrusting technique.

Then the time-jump and the next time Naruto encounters Sasuke, he discovers that Sasuke has a new upgrade to the Chidori, the Chidori Nagashi. Naruto responds by upgrading his Rasengan with the Fuuton Rasengan. Both jutsus were bigger and stronger than the originals with more destructive power, and were only accomplished with the introduction of elemental affinities; lightning vs wind.

Now Sasuke has Kirin, while Naruto is beginning his training with the toads. Kirin, fittingly, is accomplished by Sasuke using the nature energy in the air and atmosphere to produce the massive attack. Which sounds an awful lot like the description of the Sage chakra, wouldn't you say? Therefore it's pretty safe to say that whatever Naruto learns from the sage training will be to keep him on par with Sasuke.
This seems almost right, except that Chidori Nagashi is NOT on the same power level as the Wind Rasengan. The counters are as follows: Naruto learns rasengan to counter chidori. Naruto gains wind element to counter Sasuke's lightning element. Now, the particular wind technique he happened to learn first completely obliterates Chidori Nagashi, Chidori, and any lightning technique Sasuke has with the POSSIBLE (and I'm still going with improbable) exception of kirin. Until we saw kirin, there was nothing in Sasuke's arsenal that even came close to the wind rasengan as far as a non bloodline technique is concerned. In other words, chidori nagashi could probably be countered rather easily by a much less destructive wind technique than the wind rasengan.

I'll agree that Naruto's sage techniques are a counter for Sasuke's ability to make use of chakra from his surroundings. Just, not particularly to counter kirin itself. It'd be a bit overkill just for that.