Future Primals and potential implementation into lore.

[Enkidoh]

Atomos from IX.

Well, again sadly Atomos already appears in the game multiple times, even back in 1.0 (it first appeared in FFXIV 1.0 as a non-killable entity that randomly materialized over aethertyes as part of the Seventh Umbral Era events that led up to 1.0's shutdown, where it drained the aetherytes and turned them orange, and later disgorged very high level voidsent enemies like ahriman and gargoyles that would immediately agro (and quickly kill) anyone who happened to be in the vicinity (not even a party was usually strong enough to take them on).

In ARR Atomos appears as a boss in the Crystal Tower raids, firstly in the Labyrinth of the Ancients, and then later in the World of Darkness. And from what I understand, it's meant to actually be the same Atomos from FFXI (an entity that devours timelines, essentially whole universes.) So alas, a Primal form is out of the question.

There is also a rather cute minion of Atomos you can get too (this one is pink and more resembles it's FFV original).

So basically Atomos is already in the game I'm afraid.