Wasn't Turalyon really young when he had to take command? My War I and II lore is kinda hazy, but I thing he is supposed to be in his 40's now.
I think Alleria is really a wild card here. She loathes the orcs; loathes, loathes, loathes them, so she should be hardcore alliance. But her vengeance was for Quel'thalas and her family, she did it all for them, so she just can't throw that away.
But if Vereesa could side with the alliance, so can Alleria: indeed, they are the two Windrunner sisters that worked closer with the humans and the alliance as a whole. Most elves dead during the third war go horde, because they loyalties always lied with Quel'thalas and the humans were allies of convenience during the troll wars and of debt afterwards. So for the elves that never worked with humans or the alliance firsthand (i.e. most of Quel'thalas) it was always going to be their homeland.
So I think Alleria should be Alliance, but I won't flip any tables if she comes neutral (she has much more reasons for it instead of Malfurion "hush Tyrande" Stormrage); But if she is indeed Alliance, I do expect some major angst about the fate of the blood elves.
Can we just have a patch named "Windrunner" on the next expansion?? It would be glorious having an all out faction war lead by the Windrunners.