Well, there are the words out of his own mouth that he won’t lead the Horde.
So he’s clearly got the job, if he wants it, right? The line “You and I… we don’t get to hide” was even so important that it came back before Saurfang’s Mak’gora challenge to Sylvanas. He was at Saurfang’s side when he died, and he got a whole cinematic setting up his return.
Okay, let’s get the behemoth out of the way. Warchief, Warchief, who’s gonna be Warchief
