It is possible to cease to exist if the soul is destroyed. There is no coming back from that. This is most likely what happened to those who do not return.
[He's mostly speaking from experience here and not because he knows how things work in this town. It could be different, but who knows.]
@subzero, text
[He's mostly speaking from experience here and not because he knows how things work in this town. It could be different, but who knows.]