I think you forgot an important detail: The auracite that was split in pieces by Thancred.

Now I could be wrong but this how I interpreted the scene: the auracite split and the pieces embedded themselves into Emet-Selch. Combined with the "blade of light" and the scions' own aether pushing those pieces real deep into Emet's core, the latter's soul was destroyed in the very same way that Ascian that got done in by the auracite that was brought by Moenbryda back in Mor Donah in ARR.

So in short, there's nothing left of Emet-Selch's soul.