Even if they really did a FS3... after all the awesomeness we ve had mod wise I feel Volition could hardly live up to the expectation.
Would propably end up being another "Duke Nukem Forever" style desaster, possibly with rushed production and lackluster "modernized" gameplay ... certainly designed for the console market, mainstream audience and an XBox360 controller, bleigh.
At this point I am frankly hoping they won't ever make that sequel.

The funny part is that there has hardly been any mainstream game in the last decade that I was looking forward to quite as much as I am looking forward to... WoD2, Blue Planet: WiH2, Wing Commander Saga, Diaspora, et cetera.
Mainstream gaming has become a bit stale and is lacking imagination imho. Mods and indie games is pretty much where innovation and truly good gameplay are at these days.