From “Is Facebook Forever?” Rebecca J. Rosen’s Atlantic article about the overwhelming reach of the most popular social-networking site:

“Social-networking sites are fragile, as MySpace and Friendster proved. Unlike Yahoo! and AOL, whose users can get more or less the same experience if there are millions of others like them or if they are the last ones on Earth, social-networking sites can shrivel quickly if the perception rises that people are leaving.  But even if Facebook does someday flag, its reach and its repository may mean a different kind of decline than those of the social networks before it. Those houses, once abandoned, fell apart. But Facebook may be more like the house you moved out of when you went to college — a house you still stop by to check in from time to time, see how the neighborhood is doing, say hi to old friends. It’s no longer where you live, or the place you call home, but it’s never quite gone either.”