What if the Cataclysm released 7th Sha which is currently corrupting Garrosh and magnifying all his negative personalty traits, and in the Seige of Orgrimmar, we purge it from him, but then it goes to corrupt Thrall, and Garrosh saves Thrall at the cost of his own life, just like his father did.
AND THEN WE NEVER SEE THRALL AGAIN.