Sai may die...
This is either a moment cementing him into team 7 forever, a team 7 where Sasuke doesn't really fit in.....OR this is the prelude to his death. Hopefully not the death part, but this is how it seems. If he was to die, I don't know what the purpose would be for it.
Only thing I could think of is if he died from Sasuke's hands. It would definatly change Naruto's views, other then that Naruto has already matured through the death of several friends.
I doubt it. If anyone kills Sai it'll be Danzou (either directly or indirectly). The obvious question does Kishi has the stomach to actually KILL Sai? If history is any indication, and it has been, the answer is a resounding hell no.
But if he does, it won't, and really can't, be Sasuke. Sasuke may attack, threaten, maim, and so on, one of Naruto's precious people, but he will never successfully kill them because it makes Sasuke's redemption much, much harder (if not impossible) and permanetly alters his relationship toward everyone else. It would truly be the land of no-return for him.
It's hard enough to believe that Naruto and Sakura still cannot see him for who he is, but they'd have no choice if Kishimoto wanted to retain even a shred of credibility, unless the whole point would be to show how deluded they were.
On the other hand, if Danzou does...we have a new reason for everyone to hate and want to dispose of a characater who is clearly a villain.
The first would, I think, be far more interesting and has the potential to make a better story, but the latter is what would happen.