People make fun of Thrall for being green jesus, but he's always known the way the wind is blowing. He allies with humans when necessary, he allies with ogres, former slavers of Orcs to help build Orgrimmar. Becomes Earthwarder, then gives it to Wrathion. He's been Warchief up until handing it to Garrosh just before he gets axed by the Warchief's Curse.
After Sylvanas kicks the bucket I expect the Horde to lose a Warchief a day, in the end Thrall has always known when the going is good.