Found this little tid-bit of info from someone on Animeondvd's forums. This is just a rumor and its not concrete yet but according to this site Bones has let slip some rumors of possible sequels.
Its just here-say for now but if this is true then alot of FMA fans and fans of Darker than Black will be very happy.
Again this is just a rumor that I found when cruising the site so it could just be false but it still makes you wonder about this anyway.
Here's the link:
a geek by any other name
The info is small I know but thought you guys would like to know anyway.
Enjoy.