If I remember correctly, Europa is on the table for consideration. There was some concept art that was revealed a while back, one of which had a city, similar Freehold on Mars, that was overtaken by sheets of ice with Jupiter and another moon in the skybox. It is also possibly mentioned both Jupiter grimoire cards. "Old records refer to cities in ice and world-spanning oceans, but perhaps this is only poetry (Grimoire: Jupiter)." "Seafloors transform and then yank themselves skyward, shattering the icy crust. New worlds awaken in the swirling depths. You build homes around this half-born sun ripped by storms and supersonic wind (Grimoire: Ghost Fragment: Jupiter)." Interestingly enough "build homes around this half-born sun" refers to Jupiter's moons rather than the planet itself, which indicates that there is likely no in atmosphere area for us to explore on Jupiter.