Don't hold your breath on too many more new areas. Every expansion so far has had every area it would ever have, listed in the .dat containing all the area names. (Although Temenos and Apollyon got their names changed when they were released.)
So far, Wings of the Goddess has the following areas which are in the .dats but aren't yet available:
Davoi
Castle Oztroja
Beadeaux
Beaucedine Glacier
Xarcabard
Castle Zvahl Baileys
Castle Zvahl Keep
Throne Room
Everbloom Hollow
Ghoyus Reverie
Ruhotz Silvermines
Walk of Echoes
The last one is likely the funky looking place where you meet Cait Sith. The other three without are unclear (although quite sizeable, they've each got more than half a dozen map screens). There are also three - yet unavailable - map key items in the .dats, for those three areas. (None for Walk of Echoes, implying it's a mapless area, so either some sort of BC or some sort of endgame area.)
Anyway, notable places that *aren't* there include, well, everywhere else. Jeuno, Tavnazia, Selbina, Mhaura, Aht Urhgan (no surprise there), and outdoor areas aplenty. Past Jeuno has potential to be one of those "can only visit during cutscenes" places though.