We know that the infinite dragonflight serves the old gods (according to the dungeon journal entry of Murozond) and the last time we heard about them was when they helped Kairoz and Wrathion to make Wod happen and then everyone forgot about them. So, guess what? they succesfully released an old god: Wod happened and allowed alternate Guldan to travel to our reality and open a path for the legion, then at the end of the battle against the legion, Sargeras impales Azeroth with the dagger, this causes Azeroth to start dying so Magni gives us the Heart of Azeroth and later Azshara uses it to release N´zoth and so, the infinite dragonflight has fulfilled their goal.