Meaning does this cosmic conflict span across a multi-verse?
Xal'atath mentions the Eternal Conflict that has gone on longer than we know, and that the draenei were not the first group of mortals the naaru have worked with.
The Eternal Conflict also exists within the Diablo universe between the light and dark of angels and demons. The angels descended from the original "God" who separated the darkness within himself, named Anu. Anu was also a crystalline being, just like the naaru, and their names are awfully similar.
Then we have the Doomsayer Pamphlets talking about the crooked, sightless serpent that watches from the outside. Could perhaps this serpent might actually be Trag'Oul, the serpent of balance? Perhaps Trag'Oul monitors this multi-verse, being separate from Anu?
Outside Deckard Cain mentioning the Eternal Conflict in Heroes of the Storm, could Blizzard be building an over-arching cosmic war that spills into other realities, but has some nebulous reasons for its existence that we have yet to understand?