I will probably do some modding work for this at some point in the relatively near future (we're talking 2-3 months- I have a lot of FL stuff I want to get done first, and no, I won't be "leaving"- just doing some side-work).
Spring is a beautiful game engine, it's Open Source, it's sci-fi, it's totally free, and it has a vibrant community. And, um... if we sort've cross-pollinated with them, and some sort've Open Source FL "sequel" got built, I think that modelers, skinners, animators, programmers etc. could all really find a greater community and bigger support.
I know this may sound weird, but I sort've feel that TLR might have its best possible future as being sort've a "hub" for modders in general. This is one of the best-organized modding sites ever built (really, I should know- I've been to a lot of them) and if, as things move forwards, we could serve as a collective modding exchange... we might really have a nice thing going here that would last darn-near forever.
Places like Polycount already have FPS modding pretty well tied up. I think that if TLR "cornered" the sci-fi game-modding talent pool, it'd really have a lasting future as a destination site. Just concentrating on "fly-around-in-spacecraft" genre games is probably not going to work, however. There just aren't enough high-quality titles out there... and most of them have their audience pretty well locked up. The SY clan (the developers of Spring) would probably welcome having another friendly, modder-centered website that supported them and helped out with bandwidth, and I think that there is a lot of potential for FL modelers and scriptors to work on Spring mods, and vice-versa. In short, it's an excellent match... plus I'd be happy because my two favorite modding environments would be here, and I could send Spring people here and get them hooked on FL and TLR without causing a ruckus