Keep in mind, most of the these people have moved on with life or moved on to Excalibur. Only a handful of the original people visit this forum frequently. According to your chart, BC-Central is slowing down, and I agree. Productivity slows during school months, picks up during the summer and winter.
BC Technical Support also adds to the topic creation. Most issues are discussed and quickly fixed with excellent customer service.
Bridge Commander is over 10 years old, and many (including me) are surprised that it has lasted this long. Computers keep on changing, and soon BC will not be able to run on these machines.
Over the last 6 years(I think it is 6) I have been modding BC, I have taught myself 3ds Max, gained new friends, and created a website to showcase my work. BCC has become a place not only to build scifi ships, but a place to learn the tools of the trade.
Whenever BCC dies off, another will start up, and many of the same people will join (Excalibur?).