Only problem is one thing, and I ran into this when I tried writing it. The FS storyline is completely ship-based, there is absolutely zero REAL plot development that happens on-board a ship (with the exception of the commander on the Riviera in Ross 128. Even Hall Fight had no actual significance to the story at large). That means you're going to have to get real creative with the action to keep it from getting dull and repetitive. Wing Commander did a good job at this (even though everything else sucked), by having barely any space combat. Although the WC movie was helped in the fact that there was already a lot of characters in the WC universe (with the exception of Petrach, Snipes, a few others and "Command" there are none in FS2).
This means that you would have to at least significantly change various portions of the FS storyline to fit a movie format. This would lead to some odd contradictions with the fan base, which would be weird, considering the fan base is making the movie.
That's my $.02.