WOK Spoilers: Parshmen

[Pechvarry]

This all sort of reminds me of my theory as to why they assassinated Gavilar in the first place. It seemed apparent to me (of course I could be wrong) that the Parshendi needed a massive army to camp itself in the shattered plains. -Why- they need that is unknown, maybe its just to kill chasm fiends before they become something worse, or maybe its so there will be an army there to fight off an attack of unknown origin (unknown to anyone not Parshendi).
And since it's exceptionally unlikely that the Alethi would believe the Parshendi when they start describing this horrific threat, the Parshendi knew they would have to do something drastic to get them out there. Like killing their king and then luring them right to where they will eventually need them.
Just my thoughts

Just to take this idea one step further, Gavilar was changing before the end.  He was becoming aware of things he shouldn't be aware of.  If your theory is true, then perhaps the parshendi were telling him things (in private).  Things that shook him up bad.  Likely, instead of bringing his whole army out to the shattered plains where they would die in a final desolation, his decision based off of what they had to say was something more in line with "consolidate Alethi.  Weather the storm to come."  Sort of a "lock yourself in the basement instead of helping the other survivors defend the convenience store from the zombies" approach.  So the Parshendi took drastic measures to pull them out.

[CabbyHat]

I'm skeptical about the "parshmen/parshendi become chasmfiends become thunderclasts" theory. If they're out on the shattered plains to grab gemhearts, destroying the chasmfiend's chrysalises, why bother leaving their dead out where they could become chasmfiends in the first place? Maybe it's so they can have eventual access to more gemhearts, but it still seems like a big risk to take.