Akihiko Matsui wrote:
We’re planning to prepare new series of quests related to Wings of the Goddess where you can obtain Atomos as you progress through them. The new quests will involve not only Atomos, but Trust alter ego additions, and battle content that can be repeated similar to high-tier mission battlefields. We’ll be getting into the real work of this content in July of this year, and the content is quite hefty so we expect it to take a bit of time.
We’re planning to make Atomos similar to Odin and Alexander in that he will be an avatar that can be summoned only during Astral Flow. With Atomos’s special traits, we’d like his power to be another choice in the array of Astral Flow avatars.
http://forum.square-enix.com/ffxi/threads/39292-Cait-Sith-Atomos?p=507338#post507338