My thought about the woman at the top goes for Venat/Hydaelyn, looking at her Ascian attire (I actually just saw a theory that Venat is Minfilia in Amaurot because of their shared pose... makes so much sense actually, story wise).

As for the scions being the center of the expansion - it makes sense since it's a final of Zodiark and Hydaelin arc, and we probably won't need Archons anymore after that ancient conflict is resolved. So rather than losing them, we probably will see some changes in how our party operates after that.