Actually, the Void is already directly referenced in FFXIV - Eorzeans regard it as a chaotic region beyond the seven hells, hence unnatural monsters like demons, undead and transdimensional entities are often grouped together under the term 'Voidsent', as they were stated as materializing from this region.

It should also be noted that the Void is actually where Louisoix sent the original Warriors of Light during the Battle of Carteneau to protect them from Bahamut's Megaflare, where it has been stated they remained 'untouched by the passing of time' until they returned to Eorzea five years later.

So this reoccurring series element is definitely already appearing in ARR. Whether SE takes it further and actually has the player physically visit this location as an actual area in the game though, remains to be seen.