It would be sad if Naruto anime ended without finishing the entire story, but that HAS happened to many anime series before. Anime costs a LOT more to produce, and if ratings slip .. then bye-bye Naruto. It's just a business decision like any other .. so let's hope it stays popular enough to be completed.

Given the character/plot progression, if we were to take the current plotlines (Naruto becoming Hokage, Sasuke vs Itachi, explaining the past of the 4th, etc ..) to their end, the manga would probably go to around chapter 400, which would mean 200+ anime eps?