Like this idea. Proyas makes a better shriah than Maithanet, because Proyas BELIEVES! I bet Maitha just thinks of Kellhus as a bigger predator. Maitha thinks he could do Kellhus' job if Maitha just had the right blood/training.
This would all fit with Kelmomas being Kellhus' "agent in Momen."
I don't think Esmenet can/will try to name a new shriah yet. All the chaos may prevent the proceedings from occurring or finishing and the absence of a shriah makes its forces easier for her to use. Leaves the door open for Kellhus to simply decree Proyas as next shriah.
CRAZY: Psatma is elected to be the new shriah!
If we are watching the unfolding of a Jesus/Judas/Peter end game, then I think it's relevant that someone is manipulating events to make Akka hate Kellhus for stealing Esmi. That her womb would be the only viable womb seems ridiculous to me--there must be some kind of markless intervention going on. So Kellhus must take her, so Akka must hate.