Agree on the Mag'har; Iron Horde tech was one of the coolest aspects of WoD. I do think the Lightforged and Draenei shouldn't be excluded if we do get a Tinker class even if the Tinker tech is less Artificer and more Guns and Gadgets though. I'm also working on a class that would be more of a cosmic Artificer type thing, but would be really distinct and more magical than Tinkers in any iteration.
I could easily see Lightforged NPCs for example, making their own version of Tinker tech because they "just think it's neat"; we even already have that Lightforged Engineering trainer who thought the Gnome's tech was neat.