My thoughts considering the new info released are that"

The blue Mamool Ja (Captain of the Guard?) becomes leader as he is well liked and not a member of the royal family. Hard to say for certain since I believe we still know little about the Eldest brother and the "warlike" brother we are trying to stop.

As for the Enigmatic Girl, My belief is she is inside the "City of Gold" chamber/vault door and is either the lone survivor or perhaps the only one up and about while all of her people are in a suspended animation/time stopped. Upon release they all become the antagonists with her as the big bad leader.