The Nice thing about this game is that the lore is always changing. We have 3 very different Death Knight Generations over the years, Why cant we have a "new" Demon Hunter? A class that took to wearing mail with special enchants to protect them, forsakening the former fighting style for something new.
Hell if i had the time i could come up with some nice new "Lore" about a group that wants to fight demons but refuse to follow illidan's ways, rewriting the Demon Hunter rule book, discovering new ways to wield fel energy.
This group breaks into 3 Clans, One that teaches the "traditional" demon hunter style, using speed and precision strikes to drop the foe. Protecting themselves with blocks and heavy armor that does not impact their speed.
A clan that uses fel based spells to empower their arrows, attacking from afar. this clan promotes using demon magic to kill the target and escape before being seen.
A clan that binds his/her soul to a friendly target, taking the damage they would and healing them as if they were one.
If i can come up with that on my lunch break, inbetween nursing notes, blizzard could do a thousand times better.