Y'shtola seems most likely to me.
She's still building that debt using up her personal aether to be able to see and which Matoya warned would kill her eventually. It's not like Emet Selch cured her when he brought her back from the life stream. I was very surprised that wasn't mentioned during the mother porxie segment but I doubt SE has forgotten about it.
If you run G'raha in Trust as DPS, he's essentially BLM just as she is. That surprised me. I was expecting to see him go back to Archer as he was when we first met him considering his arcane ability was supposed to draw from the Crystal Tower, which technically he shouldn't be doing anymore now that's he's sealed it back off. Why BLM? Perhaps because that's a hole that will need to be filled in Trust soon just as Estinien is replacing Ryne.
G'raha's fading blood of Allagan royalty is plot armor for now. I'm expecting it to be useful when we get to the moon.