Ah yes, one of my old dreams and the actual reason why I started with game design and c++ coding in the first place. I dreamed of creating something like this eversince...
Nice to see others with the same idea, that means there's actually demand for it.
Even the "pilots can be gunners", "shivans played by admins" and the "command mode" idea is in there. Highfive for that, Davidge. We both have the same dream!
But as I grew older and gathered more insider information about the industry I came up with several reasons why this is virtually impossible:
1. There's no way to re-use the FS2/FSO code for an MMO. (Also because of the license) It's a nightmare to think about problems like simulation and AI, collision detection and all that jazz on a MMO scale. Basically the good old question: "How do you simulate a solar system". There are solutions but they remain performance greedy which makes servers expansive.
2. As headdie pointed out: managing an MMO is a nightmare. Server structure and positioning is hard duo to desired low pings for an FPS shooter. Gamemasters, moderators, tech support. There are usually hundreds of people involved in just keeping it running.
3. These servers are very expensive. A rough estimate from the gaming industry states that a medium size MMO generates about 50-100k$ monthly costs on the averange.
4. You need people(users). Lots of them. They all need a place on your server (that's where the costs come from). And most of them have to pay. Otherwise you won't be able to pay for the infrastructure.
5. Content. No one would play and pay for an MMO without enough content to fill years of entertainment. You'd need lots of content patches over time and therefor an active development team. It's never done, and never will be.
6. Sad but true: Good luck getting the license. Interplay won't give it away for free.
With all this said, I'd say the biggest problem is budget, experience and demand.
'Virtually' impossible. Entirely for a small source code project, which is a shame :C
I think the best alternative is a complete new game as MMO, in a different universe but inspired in gameplay by freespace. And maybe not even 3D, but 2D which eliminates lots of technical difficulties and saves a lot of performance for the server and network code.
Or a CO-OP mod for FSO which implements basic online features.
Some dreams may never come true...