The 8 years worth of retired WOW players who would come back to play as a demon hunter are interested in demon hunters because of Warcraft lore, and I think the whole point in fighting for their existence is to realize the demon hunter of Warcraft which Blizz has teased us with again and again.
The armored demon hunter human from the RPG art is basically a warlock, the blood elf basically a play on the wardancer wood elf from Warhammer, which the Demon Hunter is inspired in part by IMO, while not necessarily looking like Illidan, they would need the eye blinding ritual and the demonic infusement imo, and their armor sets would be based on samurai hakama pants, light overlapping plate armor, war skirts and kilts, with wide areas of exposed skin to show off their ritual tattoos. I can imagine all kinds of armor tiers that would feel very demon huntery, like this demon hunter armor concept art from Burning Crusade. I don't think that violates the demon hunter of WC3, but embellishes what an individual demon hunter hero would be, which is what we're playing if we get the chance.
In my minds eye, seeing a demon hunter in action, I mostly see a fleet footed acrobatic fighter darting around the battle field with their signature "ninja run" with rapid steps and burning fel fire or shadow fire left flickering in their footsteps, leaning forward with their blades held stiff and out to their sides like massive wings as you saw them running in WC3, when they then leap into battle in wild flamboyant movements, every strike a part of a series of chained whirling maneuvers with their circular blades spinning around them in complicated arcs, one strike flowing into the next in a perfect series of swings which keeps the momentum of the massive curved blades constantly preserved as one spinning blade strike flows around their body into the next, a whirlwind of twin blades at all times keeping any enemy away from them in the place of armor as the demon hunter darts in and out of range, the long strips of silk from their eye binding trailing behind them and flapping around with the kind of fake real time physics like you see on the Pandaren belt. I think that's something that could give them a lot of visual flavor and character, and when you stop moving at rest, the strips of cloth hanging from the knot fall down about your shoulders around your neck, like Ryu from Streetfighter 2. Perhaps maintaining an upkeep of sorts between their chaos energy/fel fire building up they have to release tactically as an AOE DPS aura, or as a concentrated blast, or by charging their blades with the fire.
I'd like to see their whirling strikes have a combo like system of procs you can chain in novel ways like that, and if you get through a full combo at the end of it you can choose to use the chaos/fel energy in multiple tactical choices like I said above.
Those are the kinds of things I'd like to see with demon hunters, as well as character customization letting you have various degrees of mutation from the fel energy, like spines or spike barbs on your elbows or shoulders or down your skin, smoldering cinders and smoke forever streaming from the blackened scars of your eye sockets, claws on hands and feet.
I just don't see the point in a Van Helsing like D3 demon hunter, which is basically a gun slinger with crossbows. I'd rather something like be used for another hero class, like the epic marksmen from the Warcraft RPG who uses rifles and dual wields pistols and muskets with a trench coat and a wide brim hat.
---------- Post added 2013-02-21 at 06:36 AM ----------
I'm not sure what a Runemaster could work with as a 4th spec, maybe a monk or shaman, but I'd love to see them in action too in WOW. Basically a brawler who only uses massively powerful and rapid machine gun punches with brass knuckles, with glowing runs all over their bodies. I'd just love to see them punching everything in rapid powerful combos like a piston. A tauren wearing nothing but a long kilt with glowing runs all over his horns and body just punching an enemy into a pulp, that would be nice.