A specific quote from one interview said:
Yes, I think that we see this initiative as an ongoing one. It’s a platform upon which we can continue to build and add. We’ve already heard tons of requests and feedback on existing customizations and things people would love to see. And while we, of course, can’t get to everything in the limited time we have, that doesn’t stop as soon as Shadowlands is out. It’s a process that will continue. There are other races you want to give attention to, and then continue to revisit just the general space of letting people express themselves as their avatars with the greatest diversity possible in the game world.
Admittedly that’s just one interview, and there’s room for interpretation, but it did kind of imply that we’d see more race customization options added at some point during the course of Shadowlands.
With that said, while they have now said they have no plans for more customization during Shadowlands, plans can change. Though given how far behind they seem to be, that doesn’t seem likely unless the artists can catch up on the backlog they obviously seem to have.
After Blizzconline’s disappointing announcement regarding customization options, if nothing changes in the interim, the best we can hope for right now is more options in 10.0 pre-patch, and even that isn’t guaranteed.