Caveat: right now, this is just a bare-bones scheme on paper. Details may be subject to change in practice.
I want to promote staff collaboration at both levels (ST/Mod), everybody being sounding boards and discussing ideas together and cooperating to realize them. Ideally everybody of a rank should be at least aware of what their peers are working on. So Moderators will have a specific collective development board. I'm not wholly sure what everyday development will happen at that level, but I tentatively think it will involve more history and factions than races/polities.
Possibly also some high-level direction for ongoing plots. STs should manage scene-to-scene, with maybe some hooks for future scenes. Senior STs should be managing whole seasons, with an eye to groundwork for the next season. Mods should be thinking multiple seasons to a year down the line, looking at plotting in context of the future of the game, and otherwise providing the framework that STs of both levels will fill with details.
There will be times when new races/cities are developed, but only when there's enough ST/Mod support. There will probably be an ongoing draft board for working on new nodes (a group of polities/races), but nodes won't be released until the community can support them, and they will be released wholesale rather than piecewise.