There are several predictions about declining of blogging. Today there are so many kinds of blog, personal blog, wordpress, myspace, comercial blog, mini blog (twitter.com), spam blog, vdo blog. Basically, too many blogs and blogging had already pass a peak period.
Some people just run out of idea to write, and run out of gas. Thus the velocity of blogging is decreasing. Who still have new idea will continue blogging, the others won’t.
Thus, don’t mind your friends’ blog disappear from blogging society.