The end is that what matters, and by the looks of it, Varian is just like: "We killed Garrosh! Cool, have a new warchief, we are going to stormwind for a party now, cheerios!"
How did the alliance use the darkspear exactly is beyond me. To Kill a leader that is actually the reason for the horde falling apart and change him with a stable leader that can make the horde even more powerfull and then leave? I, as an alliance player, feel used.