My wager would be the Light. Varian isn't even saying anything new here it's words Anduin has heard before almost like a dream. We already have plenty of situations where the light uses Anduin, the most recent being for Calia Menethil.
I'm really hoping we get an arc with Anduin and the light. Imagine a X'era-like situation where a Naaru picks up Thrall or Baine and he had to choose in either intervening or sticking with his faith in the light. I would love to see that sort of dilemma for our boy.