For those of you that don't know, the evokers starting experience has a few books detailing the origins of the dracthyr.
One of the books states that evokers are the elite of the elite, meaning that not all dracthyr are evokers. This was my original theory as to how we might get more classes added to dracs down the line.
With the obsidian wardens and dark talons joining the alliance and horde, it's inevitable that some dracthyr will want to pursue the way of the warrior or mage.
Will it be for the final patch of DF or maybe at the start of 11.0? Who knows but it's more than certain.
That being said, what classes will dracthyr have, assuming blizzard doesn't open up all classes to all races....
Now warrior, mage, rogue, hunter, and priest are a given. Since all races will be all of those classes come DF. But what else....
DK and DH, unlikely as they'd need an entire new intro.
Shaman and druids, Dont see why not. Though perhaps the conflict between the primalists and aspects might be a reason not to have shaman.
Monk, 4 limbs, check.
Warlock, if there isn't some silly lore that dragons are against using fel, then sure.
Paladin, the dragons connection to Tyr mean ls they'd probably join the silver hand in honor of Tyr. There's even a statue in thaldrazus with a Female Titan keeper holding the silver hand.
So there you go, I already started creating a drac paladin I'm the wowhead dressing room for the day they're available