Random picture of concept art doesn't confirm anything. Please stop throwing that word around, its getting really annoying.
I have to agree, the fact that there's concept art at least implies they're considering including something, but it doesn't guarentee it will make it into the game. But creating more than one version of a creature isn't that hard, so I wouldn't be surprised if they're in, though hopefully, they're more than just a recolored version of the game creature with different stats as you get in games like Diablo and actually look and behave like a different breed/race/species in the same familiy. Still, people really need to stop saying the word "confirmed" so easily, you can say "This suggests so and so." but you should only say something is confirmed if it actually is.