Well, the game is indeed popular and mobile gaming is always going to continue being in demand. I see gamers everywhere on their phone...
I agree with your thoughts, iOS first and Android later. This is a common strategy for game developers. But Android does have a larger global market share, which would allow the game to roll out to the largest audience.
The hard part would be trying to translate the game's control and mechanics to a touch-screen device. The graphics should scale down relatively easy, but then you will need to make design changes for a wide variety of mobile graphics hardware.
No idea how you would choose to monetize it. You could follow the same PC model of free-to-play with a micro-transaction system of some sort.
I like your idea of fan developers. Just make sure the PC community can crossplay and communicate with the mobile version, because the community will continue to be a huge positive.