This. I doubt we'll have any more allied races in BfA. We get maybe 2/4 for the pre-purchase of the next expansion though.
People who thought we get new allied races each big patch this expansion have been delusional from the beginning.
Mechagnomes and Giblins come to mind with Tinker being the new class. So that could be some kind of super-prepurchase-bonus then. Two new distinctive allied races that can exclusively play the class (next to usual Gnomes and Goblins).