This thought just occurred to me. With the catastrophical consequences of Garrosh's reign, could the position of Warchief be abolished or at the very least reduced to a military rank only and no longer acting as the supreme leader of the Horde? I noticed that Vol'jin was never really referred to as the new Warchief; Thrall just stated that Vol'jin should lead, and when Varian called out for the Warchief, Vol'jin only stated that he "speaks for the Horde". This just left me wondering.
I think it'd be quite symbolic for the Horde to give up this rank so the leader of the Horde would no longer be automatically associated with warfare. It would very well reflect the change that is going on within the Horde now.