I think the question of how, if at all, Ultima (being) is related to Ultima (spell) has a real chance of being answered soon.

Since this image from the trailer never showed up in any of the 5.2 quests so far:

Then unless it's in Ishgard Restoration for some reason we can safely assume it's from the relic quests and therefore depicting her, since the relic quest will require completing the Ivalice raids.