War against the Void.
War against Iridikron and his minions.
War against the Infinite Dragonflight.
War against the Legion if they ever return.
War against the Naaru if they ever follow through with that arc where they were forcing everyone to get Lightbound.
War against any PvE threat they can drum up.
Did you know that Warcraft 3’s storyline probably had less than 10% actual Horde vs Alliance?