Pssst, the Viera in XII were never female-only lorewise, they were female-only in the sense that we only see females but their society is actually very segregated to the point that males and females live in separate villages and only get together to mate. Meta-wise, we only see female viera because...well, bunny girls = boner money.

Yoshi-P already confirmed no new races for Stormblood, but since the demand for playable Viera is pretty overwhelming AND they already have concept art, they could change their minds for 5.0 given enough support.