Writings of the Void

The quest explicitly states that being/becoming a Demon Hunter is strongly "frowned on" by many of the Night Elves, probably mostly due to Illidan's bad example.

Arcane magic is frowned upon by night elves but they can be mages. Demon Hunters are frowned upon because it usually requires the aid of the burning legion to be one.

While unpopularity/hate from the major populace didn't stop other classes to be available (Warlock, Death Knight) I doubt that one single quest involving the ghost of a Demon Hunter foreshades playable Demon Hunters.

why? if they haven't announced anything yet, why would they add absurd amounts of foreshadowing? I wonder how many have found their way to him in those ruins is textbook foreshadowing.

BC had you working for an independent one and fight four Demon Hunter trainers, so that doesn't mean much.

your right, that doesn't mean much

Even if they are considering a new class after the DK (near-)debacle, a tank class that didn't increase relative tank numbers,

We still have plans to introduce new Hero classes in the future.
they are considering it.

what would be so unique about a Demon Hunter?

what's unique about any class these days? the resource system. i'm sure it wouldn't be that hard to make a good one.

Portions of this lore class have been incorporated into rogues, hunters and warlocks already, so a Demon Hunter as its own class can not really stand out.

so? parts of the death knight existed in the warlock (they even share an ability with the same name) also, hunters haven't taken anything from demon hunters other than the name and tracking demons.

TL:DR
my rebuttle to Nathanyel

Eh. You have to go kill a demon hunter at the bottom of a swirling pool. We get to ride a big explosive rocket in a zone that's the shape of our symbol

If you do a 3D view of Illidan and Telarius, you notice some distinct differences side-by-side. Sure, one could chalk up the differences to being "his demon form" or something. But take note of the markings. While very similar at first glance, a closer look will show them being very unique of one another. Also, the hair. Telarius's hair is green. Illidan's is black. Ears are slightly different. Again, I suppose this could all be attributed to his demonic influence? But I doubt it.

IMHO: I imagine Telarius was more than likely some poor sap recruit who still had his recruitment flier on him - being that his level is in the mere teens. Especially given the supporting text of this quest. He couldn't hack it, got trapped in the whirlpool or whatever. Died in Deathwing's path and became a ghost, who knows? I'm not the Fact Checker. But it's logical. As for the "You are not prepared" bit... hey, it could be the demon hunter motto for all we know.

Also, Blizz does adore throwing in obscure, but blatant hints. Like the release date of Cataclysm was "leaked" intentionally in an obscure reference in-game. Of course, everyone guessed it. This could be a similar not-so-subtle 'hint'.

Blizz has also stated, they do intend on other hero classes, just not "right now". I think this was because at the time they were focused on getting Cata launched first. One major catastrophe at a time. heh

Plus, it extends the shelflife of WoW if they can launch one major change at a time, instead of all at once. Then there's all the resources into creating, editing, testing, editing, testing, testing, editing, etcetera, ad nauseum.

Do I believe this to be a hint? Sure! Why not? It's fun to speculate. And if it isn't? So what? I mean, really. You know work doesn't stop when they launch a major expansion. The creators don't sit around and QC what's launched. The thinktanks have already started on the next one, and it's just a matter of time until they unveil what they've decided on. And rest assured, it will have a buggy and rocky start just like every other major upheaval. Besides. They have to have SOMETHING for Blizzcon. I suspect they actually have the next several expansions penciled out, if not more.

Until then, enjoy the ride. :-)