I really don't see a reason for Sai to get killed, it's more likely that Itachi is gonna get killed by Sasuke/Naruto in a later fight. Sasuke can't die btw, that would be too tragic since Naruto's ultimate main goal (besides becoming hokage) is to bring him back to Konoha. I think it would be REALLY cool if the Akatsuki "sucks" out nine-tails and Naruto half-dies (in some way, I think he'd survive that) then the Akatsuki gets beaten up, Sasuke watches Naruto "die" and kills Itachi in anger. Then Sakura cries and Sasuke goes all emotional, then all of a sudden Naruto "lives" again, but the lines on his cheeks are gone, because the nine-tails was sucked out. The team goes back to Konoha, the sound nins are defeated, the Akatsuki are no more and Naruto gets promoted to Hokage. Oh, everybody picks on Sasuke because he's gotta redo the Genin Exam.
I don't wanna see this happening in a near future though. I'd really like the series to keep going a while, maybe enough to fill in three or four arks before ending the series.