My thoughts are that LFS has been kept alive over the last 6 years, mainly by a lack of competition. Other sims have come and gone, but none have been able to match LFS in 3 key areas; physics, multiplayer and value. Sure, numbers have dwindled significantly, but many people are still keeping a close eye out for updates as, although they may be bored with the content, there is still nothing out there that's better.
For the first time, it has a true competitor. The very promising Assetto Corsa has (I think) covered physics and value very well, but it has no multiplayer. The AC multiplayer release might seal the fate of LFS. If it is released before the next major update to LFS and is good, then it might be the end. If Scawen can get the update out first, or AC multiplayer sucks, then who knows.
My thoughts only, of course. ☺