This "confirmation" was found in the Game Files for NPC's and player races. Doesn't mean they're final. I won't jump to any conclusions until I see the classes officially stated on the main WoW webpage. The current class set might aswell be added for the sake of customizing NPC's of these races, and the reason why I think these aren't final is because in these files Dark Irons can't be Paladins and Priests. Paladins were confirmed and their leader is a freaking Priest.
I also want to remind people that Gnome Hunters were put in Legion as an afterthought.
Troll Warlock and Dwarf Warlock were added in Cataclysm after player feedback from Blizzcon, because Warlocks didn't get any new race combinations among the original races.