Illidan will be resurrected his body and his soul will return once more on Azeroth. But not as a good guy, like HERO that will save night elven Society and world from Burning Legion. No he will be Weapon for Legion. Sargeras will offer him a great power to fulfill his will and promises even more if he succeeds in weakening Races of Azeroth and opens portal for him to Destroy Planet. Power-obsessed Illidan will accept the gift and become Leader of invasion of Burning Legion on Azeroth. He will be our final target for next expansion. Night elves will gather elite group with Tyrande and Malfurions leadership and go to Talk to Illidan, as Tyrande still believes he can be saved. But when they arrive there they will find him completely mad from Fel energy and in answer Illidan will Attempt to kill Night elven Sentinels and druids. In the Fight malfurion will be wounded by Illidan. After realizing that there is no stopping of Illidan that They need an expert/elite team and people who know Illidan very well (his strength and Flaws).
When they get in Darnassus Malfurion talks to Tyrande about Maiev. Begs her to find her, despite what she has done to him, and try to negotiate with her, because only she is capable to slay Illidan. Tyrande calls Heroes of Azeroth to find Maiev. There will be scenario where we come across Maiev in Felwood, Shrine of the Deceiver Barrow Dens with some bend of Night elves and Broken. Where you fight her. In the end she stops (realizing it is usless to fight ). Tyrande tells her about Illidan. Shocked Maiev grasps in disbelief, but later Pleasure and joy, that her hunt will continue, masters her. She tells Tyrande that she will help them but Maiev will be Co-ruler of Night Elves and that she will again be Leader of Watchers and continue to train new generation. Tyrande agrees on it and thats how Maiev returns in Darnassus. But Maiev agrees to be "healed" from her mental wounds by Priestess and Druids.
With Maievs return she brings new Class with her calls them Shadow Stalkers, a class similar to Wardens in combat.
Armor Type - Mail (might be plate too)
Weapons - Daggers, Dual wield (Swords, maces), Polearms and Umbra Crescent
Ranged and Melee dps and Tanking specs.
Shadow Stalkers (Wardens) use thei throwing knives expertly that allows them to be good in Ranged combat, if they Target comes closer they can use expert traps to stop enemy (Maiev Shadowsong uses traps in Wolfheart) unlike hunters they use them in short distance and only paralyze them. Also they use Heavy damage skills using small bombs of Poison and also to distract enemy. (it will appear only in skills not as weapon type). They use blinks on very short distance but have little cooldown and are hard to catch.
Another spec that uses some Range skills (mostly for fight starting). They can start encounter with Glaives and for Melee they use Umbra Crescent (or dual wield). Unlike rogues they are slow in attacks but same flexibility. Using shadow magic to slow and debuff target cause them to sunder armor and diminish their attacks/healing. They serve to be good foe dispatchers. They use their skills to empower damage but risk to be easy targets (increase damage received).
And final spec will be Tanking, Like DK-s and monks they wont use shields. Mainly useing Polearms and Umbra Crescent they use weapons to parry enemies attacks and Blinking moves to dodge them (Defensive skill). They use shadow magic to guard themselves. In case of extremity they spawn a great Shadow (in WC 3 it was called Vengeance ) that embodies them and takes part of damage to itself but Shadow Stalker loses damage as Vengance grows weak (dies) and when it dies they return to normal condition.
Tyrande convinces Maiev to send her loyalties (Broken) to Horde and inform that Illidan is back and with that act Shadow Stalkers are introduced to Horde. When Broken arrives in Orgrimmar they find that Horde is already aware of Burning Legions plans.
I Hope Burning Legion Epxansion will be focused around Night elves and we will see them Awaken once more. We will the the ferocity and Bravery they had in WC3.
As for Horde I guess Orcs once more will play big role on defeating Legion and make their Redemption by it !
EDIT : Not shadow stalkers because it is associated with Rogeus. As their concept for concept for all things is Justice, it would be better to call them Justicars.
Interesting facts about Wardens
"The night elf, Cordana Felsong steps from the shadows as if emerging from a dark pool, her delicate features forming in front of those she encounters. Tall and lithe, she wears no armor but carries an impressive silvery blade as if it weighed nothing. Her cool gaze sweeps across them, and they feel as if they have been judged - and barely deemed acceptable. Cordana uses her spell-like abilities to appear and disappear within shadow. She casts silence first, to unnerve her opponents and to prevent spellcasters from using verbal spell components. Then she targets one foe and appears from the darkness nearby, attacking swiftly and retreating for another pass."
They are night elf only, but it is conceivable that a night elf could teach the skills of a warden to a member of another race, but so far as anyone knows, this has never been done
All current wardens are members of the Alliance, though it is possible that a warden might break from the Alliance after learning her abilities. Night elves certainly don't train wardens who are not loyal to them
Drelanim Whisperwind - Most surely Tyrande Whisperwind's relative.
Saria Nightwatcher - Warden and Argent Dawn Templar. Known for her two unique abilities: "Saria's Crown of Divinity". It causes a halo of light to appear over a subject's head, giving off light equivalent to a torch. Great resolve bolsters the subject, and they also gain immunity to fear and improvement of moral against mind-affecting effects
And improving Shadowmeld ability (Night elf Racial) to Lesser invisibility and later to Greater Invisibility.
That person shows that Wardens are capable to use not only Shadow magic but Holy too. Improve their abilities.