That'd be an interesting way to handle it. I'm still pretty confident that BFA will be rounded off with 4 more allied races, but if vulpera qualify as a new race, then what does that mean for the deep sea jinyu? They'd be a strange combination for 9.0, but I can think of a few ways it might work.
Say, for example, the deep sea jinyu take some time after 8.2 to establish themselves again, so the player experience going 1-15 or so would be all about what happens after the Horde and Alliance roll out of Nazjatar. Vulpera, meanwhile, might go through something similar since the Faithless were defeated and the caravans might need to be united or something.
Gilblins and junker gnomes, meanwhile, could just be pretty easily scooped up and taken with us. I still think vulpera would work fine as an allied race, and until we see the gilblin models that's my current guess at what they'll ultimately be, but I guess making them into a core race is totally possible too.