It isn't just FB's problem, and it is not becoming a new Yahoo (it is becoming a new MySpace). ^_^
The vision should be a little bit broader (and scarier to those invested in it and its clones) - OK, every teenager in the world already has a FB page and uploaded some photos of herself and exchanged some stupid messages with so-called friend. Wow-impulse has faded away. Now what? ^_^
Don't even try to say 'the next facebook' - it will be 'just another social site', af FB was for MySpace or Livejournal's addicts. ^_^
What it could be? Ok, something like a cam on your clothes to broadcast 24/7 via some G5 GSM directly to some datacity which sends it back to your personal 3D movie hall (forget Youtube with a that crappy flash player)?
No, I don't think so. The time of the mass-exhibitionism in the net is, it seems, over. ^_^