Uhm, I think you mean "Alleria won't suddenly go all Vereesa and make it her life's purpose to murder every single person she went through the Dark Portal to protect."
Turalyon being neutral would be dumb, though.
Alleria shouldn't be pro-Horde, but she shouldn't be anti-blood elf, either.
I'm sure she'd understand her people doing what they had to to survive by sucking mana from vermin like mana worms so they had the strength to fight the Scourge way more than she'd just understand that her husband's prince personally led the army that slaughtered 90% of her race, along with her sister, then the remainder of her husband's kingdom sentencing not only her prince, but also 15% of the surviving population to death, simply for doing what was necessary to defeat the Scourge without getting themselves killed.
It's ridiculous to think that she would side with:
1) Humans from an entirely different kingdom than Lordaeron (also Gilnean humans, who are sort of just squished together with Stormwind now)
2) Ironforge Dwarves
3) Night Elves who banished her ancestors for practicing magic (which she is also addicted to)
4) Draenei who she would know nothing about
5) Worgen who she would know nothing about, but might not react kindly to
6) Pandaren she would know nothing about
7) Gnomes, eh, maybe not so much them, she probably likes them after Gnomergan gnomes helped in Outland. They seem nice enough.
Over the majority of her surviving people. After she finds out what Vereesa has been up to by being a bitch to innocent blood elves and blaming them all for Rhonin's death, then just rolling over and letting Garrosh, the one single individual who was actually responsible for his death, go free, she'll realize that she should work towards helping her people rebuild, rather than help her sister pursue misplaced vengeance.
The most likely outcome for Alleria I think, is that she'll try and bridge the gap between the Blood and the High Elves and try to patch things up. She won't go "FOR THE ALLIANCE DEATH TO ALL ENEMIES OF THE HUMANS" simply because her people were forced to side with the Horde after being betrayed by the Alliance in TFT, then again in BC.
The only thing that makes sense for Alleria is for her to be neutral. She won't hate her people simply because her husband (or boyfriend, dunno if they ever actually got married) is in the Alliance. Her subordinate, Auric Sunchaser from Allerian Stronghold, is of this mind. He is the High Elven representative at the Sunwell and the highest ranking high elf from the official Thalassian government. Vereesa gave herself the rank of Ranger-General, when previously she'd been just a plain old nobody Farstrider. And the Silver Covenant have no political standing in Dalaran, unlike how the Sunreavers did. Basically, all the Silver Covenant are is the WoW equivalent of a crazy militant group of racist gun-slinging hillbillies in the woods calling themselves a militia.
Unlike Vereesa, he is trying to do what he can to provide a peaceful existence for those under his care, while she's doing all she can to cause contention and violence.
We'll see what happens in Legion, if she's still in Dalaran. I hope she is, and she has learned something from War Crimes. She doesn't have to like the Blood Elves, but if she's willing to be merciful to Garrosh, who murdered her husband, she should be able to stop pretending the Blood Elves as a whole had anything to do with Rhonin's death (Thalen was one elf, and you don't swear vengeance against everyone with the same eye color as the person who forged the sword someone used to kill your loved ones).
Turalyon makes sense as being Alliance, but Alleria does not. At most, she makes sense as Alliance with ties to the Blood Elves and a resolve not to fight them, like Jaina was Alliance and had a treaty with the Horde (when Thrall was in charge). It would be throwing a monkey wrench into her character and would be such a waste to have her just be another racist Vereesa clone.
Judging by the fact that the Marksmanship artifact weapon is her bow, available to both factions, she's probably gonna be neutral, which makes sense (though I doubt she'll like the Orcs, Trolls, and Undead, except Sylvanas. She'll probably be indifferent to Tauren, and won't like goblins much, but not as much as the trolls and orcs, as she'll know that goblins are just mercenaries and merchants).