I'll quote Kishimoto on this from Naruto Manga Volume 48:
"Ever since I wrote in the author's note of the previous book, volume 47, "The finale having been settled, I am drawing full steam ahead," lots of folks have been asking me, "Is the series ending soon?" but it is simply that the premise has been set; it will keep going for a long, long time! I shall not stop drawing at full steam, so please continue enjoying Naruto until the end!"
- Masashi Kishimoto 2009.
This was in the volume covering the end of the Pain arc and the beginning of the 5 Kage meeting arc. Now it's 2012, so one could only speculate how long a "long, long time!" is. But basically, I believe that the manga will reach at least 700 chapters, and that there might be a new time skip after this arc, at the end of the war, so yeah, I agree with the OP, but I think 5 years is overdoing it. Maybe 3-4.