i don't think they would do anything that would require a completely different model.

What I would like to see is
Hyur/Elezen mix race like Hilda which is basically hyur with slightly pointy ears, with maybe new face options
A new Miqote clan that is more feral like in that they have both the eyes of the sunseekers and the fangs of the moon or even have more variety of tail option like fox tails as one example. Perhaps their culture could revolve around hunting powerful beast as a test of courage and strength and their connection with nature. (thinking like Norn culture in Guild Wars 2 although a little more matriarchal)
Lalas from a snowy mountain place with pale/blueish skin and facial hair options to better match that dwarf theme. dwarves of the first were pretty cool, to bad their beards are a lie.
If they ever get roes that don't have square noses and sausage arms I will likely roll a femroe. Perhaps somebody like Gosetsu as an example.

I honestly hope they just expand customization more. For example, I'd like more racial focus tattoos that are not just limited to the face. Let us put tattoos in other places as well like arm/arms, torso/back, and leg/legs with the option to only have one side have one. Allow us to use mutliple tattoos as well... and not just be something tacked onto glam. Give miqote tribal tattoos, give elezen emblem tattoos, etc. The tattoos is just an example of something that could be worked on.