My thinking of the first ones is that they are not as much actual being as they might be a concept, like giving personality to a cosmic force and what they represent.
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I still want further development of titans visiting Draenor and the old god trying to be summoned in Shadowmoon Valley on Outland. And then there is also one of the Invasion points in Legion where we se tentacles and other old god stuff.
Just because we have mostly dealt with the 4 on Azeroth doesn't mean we will never deal with them again.
If we're going to have a cosmic force expansion my #1 wish is to have it be located on K'aresh, since lore seems to be pointing to it being a titan soul that was devoured by the void and for all we know the manifestation of Dimensius that was killable might not mean he is actually dead.
And K'aresh expansion would allow us to have a modern graphics Outland style continent