Do we really know for a fact that they killed the sound 4 guys? I'm not sure it was mentioned in the manga.
Sasuke hasnīt killed anybody yet (a line Neji, Chouji and Shikamaru (if Hidan wasnīt immortal) have crossed)
Could be they just passed out.
If it wasn't confirmed than they are still alive I think.
Best example is Zorro. He said to mister 1 that he won't see how Zorro cut steal because he was dying in that moment.
But as we know mister 1 didn't die.
"For Feanor was made the mightiest in all parts of body and mind, in valour, in endurance, in beauty, in understanding, in skill, in strength and subtlety alike, of all the Children of Illuvatar, and a bright flame was in him"