If I understand correctly, you want to create compilation of:
- big scale shooter (huge map, capturing checkpoints, vehicles, minimal MMORPG elements),
- RTS from soldier point of view (player is only one part of huge machine, base tech tree, getting resources and developing base with other players, global goals).
This is the opposite of 99% of MMOs, where 95% of time you are taking care of your character (exp, progression, gear) and only 5% on game community. This is very risky, because most players are egoists and mostly care about their prestige in community. If they put much effort and don't get satisfactional reward (ex. unique title, warpaint, vehicle), they could leave. This works perfect in Firefall - buying another vehicle or glider only for unique look or spending tens of hours for time-limited event titles. This and few other factors create bound between players and game which survived long after destroying (launchning) game.
If what I wrote above is not completely wrong, I understand that F2P would be a suicide.