ok so what i think is gonna happen is that both faction leaders voljin and varian die. however they key part sylvanas plays is not of the killer but the savior of one of those characters. i remember seeing some blizz writing saying sylvanas was going to try save soul or her people. what if she is trying to get a Valkyrie or become one not to save herself but so she can bring one of them back to life in effort to help combat the legion. it might go against her character a little but it would defensively be an interesting character ark, they could also make it so greymane is actively going against her which at some point stops her from being able to res the second person but finding out straight after that he fucked up.
I play horde so i might be biased but the alliance has some pretty meh leaders at the forefront without varian, anduin is too nice to win a battle with legion, magni is in ulduar, tyrande while old and wise etc has not really done much of interest, velan is very much a pacifist and malf is neutrel, the only one it leaves is the leader of the worgan but he is too...agressive? hot headed? i dont think he would be able to effectively lead the entire alliance against the legion and the gnome leader is more a tinkerer than anything else. they need varian in my eyes to continue fighting the legion. from the horde perspective he is the only one capable.
or if worst comes to worst they fake their deaths and go to ulduar with magni and receive mighty morphers and become the justice league with rexxar leading them to victory in his batman mask!
lol im sure some alliance players and horde players might think this is stupid but i think it would certainly be different story of sylvanas than what everyone else is coming up with.
also this should probs be in the legion thread...my bad