Well, FFXIV got already every common race you find in any other MMORPG:

The human race: Hyur
The elf-like race: Elezen
The tiny/cute race: Lalafell
The big/orc-like race: Roe
The sexy (furry) race: Miqote
The demonish race: Au Ra

It wont make much sense to add a new race with every expansion. Add Viera with 4.0 is absolutely fine. But it should be last race for a longer time. After that, they should better focus on a deeper costumization, because there is alot unused potenial.