Today Blizz released “Safe Haven” trailer. Blizz want to “de-throne” Sylvanas and bring Thrall aa new chieftain. So i presume it doesnt matter the decision made in that quest, the outcome will be the same, even if you choose Sylvanas. At least this is my conclusion after i saw the trailer.
As usual, Blizz put us to choose and after they do what they want, no matter our choice.