Even after having huge roles in past expansions, I'm kinda dissapointed in Thrall's character development through out Legion. Therefore, I kept wondering whats gonna happen to Green Jesus. 2 Things, A: mental issues regarding Garrosh & B: not wielding Doomhammer.
My theory is he's picking up Gorehowl. Like the "Lords of War Part Three – Durotan" showcases why Durotan wears his pets fur, Thrall can pick up that sweet axe as "... constant reminder" of his Garrosh-history-mistakes.... maybe even jam in that Shaman-Orderhall-Doomstone for... epic reasons.
Cheers