I can see Geomancer having an easier shot, why? Because of a mechanic that the devs had already worked into the game. The catch is that means instead of being a Job whose effectiveness depends on the terrain, it would be a Job whose bread and butter is altering the terrain.

ACN, DRK, WHM, and ARC set a precedent for Abilities that affect the environment in some form (Shadow Flare, Sacred Soil, Asylum, Sacred Prism, Tar Pit, Salted Earth and Flaming Arrow), but they are usually limited to two per Job (and in DRK and WHM's case, one of them is PvP only). I can see a class that is centered around this mechanic and uses it for support. Like say A Floating wind platform that increases speed and evasion, a ice area that serves as a Shadow Flaresque DoT, a defensive earthen area, etc.