Thrall - Unlikely as he had to be recruited in the first place and made clear he doesn't want to lead (though this could echo his own words regarding Vol'jin)
Saurfang - Nah, i think he's the character whose death will basically make everyone come together, Saurfang also clearly having a deathwish supports this.
He however will be the "kingmaker" of the next warchief.
Baine - Spoke out against Sylvanas, has acted against Sylvanas, was punished by Sylvanas.
Unlike Thrall, he was in the action the entire time, didn't require anyone else to join the rebellion, in terms of role, his one is the closest to that of Vol'jin in MoP.