As I said in my Saurok Megathread, the Saurok as we know them likely would not join at all, and it would likely take a new tribe that has evolved and formed a civilization, while being in a position to need help from the Horde and vice versa, to have a chance.
It’s a very uphill battle, but we’ve seen some NPC races get changed or lore added to game them playable. In fact, Gilblins use to be all male and just want to horde treasure, but currently they’re an allied race candidate with a female model and that group has some backstory. Anything is possible with a little creative writing, and I plan to support Saurok as best as I can, along with the other races I want. 