I think Otonashi is the only one that truly died. He's the only one who's death is shown. Everybody else's death (for now) have been somewhat ambiguous. We didn't see Yui, Hinata or other people's actual moment of death. So, I'm sure all of the SSS members are actually just unconscious in real life, and disappearing from where they are actually makes them wake up. If that is the case, then Otonashi is stuck in there forever, showing whoever appears in that world the way back to their real lives, by helping them fulfill their desires most likely unachievable in real life. Otonashi becomes the God of that world.
I think Otonashi is the only one that truly died. He's the only one who's death is shown. Everybody else's death (for now) have been somewhat ambiguous. We didn't see Yui, Hinata or other people's actual moment of death.
Too bad, the novel has shown how Hinata died.(dunno about the other tough)