Said it before (on another account) but it will be us who are gonna be the Warchief of the Horde in the next xpac.
It would be obscene for them to choose anyone else plus it will be the gimmick to sell the next xpac and cant you imagine it the wartable in the throne room.
Also the title of High King doesnt have to be a human king that title is pretty much like the title of Supreme Commander during WW2 plus who knows maybe Anduin dies in BfA and 'Wut a Twist' that would be!