The truth is u lose only 1 of your leaders and he is Vol'jin. Lose Garrosh who is not really a leader just a replacement and the original is there, they don't really wanna change him, but he need a bigger scene and can go back (and He is back). Cairne never do anything and he have a morally same replacement, his own son. You not lose Sylvanas she just in to many movies so she is in deserved vacation. Allliance lose 1 dwarf king and get his daughter in his place so its fine, Like Varian his son follow him, so not really lose any Leader. (I Hate Anduin as a leader) Or who u wanna get Back really?
But the truth to be told i want the alliance the aggressor and u lose OG, but i wanna see that in game not in a book and the way a Horde got this wins without any consequence.