Demon Hunters - At this point I doubt they'll ever be in WoW. Any real "demon hunter" abilities have been given to Warlocks with what few melee abilities handed to rogues. Also CM armor for Warlocks is totally Demon Hunter looking. Makes sense too given that Illidan is essentially the first "real" warlock, but still a bit sad.
Tinker - The class just isn't serious enough for WoW, I know a bunch of folks have their nerd-hackles all goosebumped up at the idea of them showing up but pretty much the entirety of their abilities can be found in the engineering profession. Far more likely to see it in Hearthstone, though odd since they've already made the High Tinker a card and he'd be the best "hero" to have face the class.