A few thoughts... all of this is totally unscientific, unverified, subjective, biased, and may be a combination of wishful thinking, drug-fueled fantasies, fever induced delirium, etc. It's almost certainly contradictory, not self-consistent, and comes with no warranty or guarantee. IANAL, YMMV, HTH, WTFBBQ.

1. Facebook can be knocked off their perch. Facebook almost certainly will be knocked off their perch, probably sooner than later.

2. The "net crowd" is very much a trend-following herd... if something catches the attention of the right set of early adopters and the avalanche starts, it'll carry through to its inevitable conclusion.

3. You won't beat Facebook by building a better Facebook. Nobody cares about something that's just like Facebook but a little better or has a couple of new features. One killer new feature, maybe. But what?

4. Facebook is not cool anymore. Facebook is a utility, like the phone company or the people who provide your electricity.

5. The way to beat Facebook is to build something that is new and unique, but subsumes (most) of what Facebook does. Think telephones replacing the telegraph. A telephone isn't a telegraph, it's a whole new tool, but it obviates the need for the telegraph.

6. Remember what Henry Ford said "If I'd asked my customers what they wanted, they'd have asked for a faster horse."

7. Go back and find and read Om's article about how "social networking is just a feature." That vision is partly coming true, but Facebook is fighting to extend their tendrils into every other site, rather than letting other sites implement their own social networking features and (possibly) combining them using open standards to build a federated social network.

8. Relative to (7) above, see: http://www.w3.org/2005/Incubator/federatedsocialweb/ and also research what Appleseed, Diaspora, etc. are doing. There may still be a chance to gain some traction for this federation stuff. That would open up some interesting possibilities down the road and could disintermediate Facebook.

9. I'm going to guess that whatever replaces Facebook will have a basis in the mobile app world, first and foremost, not the traditional web world. The smartphone carrying, app using early adopters will latch onto something cool that comes along...

10. Your mom, your grandma, your uncle, your boss, your ex-wife, your ex-girlfriend/boyfriend, etc. are all on Facebook. Your neighbors dorky 8 year old kid is on Facebook. The nerdy guy in Chemistry class who's always undressing you with his eyes, is on Facebook. Facebook is generic and boring... it has utility because of network effects, and because everybody is on it... but it sucks and is lame and isn't cool because, well, everyone is on it.

11. It's cool to hate on Gladwell, but read The Tipping Point if you haven't already. Then chase down some of the stuff by Watts, Barabasi, etc. on network science. Maybe even read Diffusion of Innovations by Everett Rogers. There's a growing body of science that speaks to how things happen in networks... there may be something interesting that falls out of thinking about "preferential attachment" and power law distributions and scale-free networks.

http://en.wikipedia.org/wiki/Preferential_attachment

http://en.wikipedia.org/wiki/Scale-free_network

12. Also, go read this old Jamie Zawinski piece: http://www.jwz.org/doc/groupware.html Keep this bit in mind:

That got me a look like I had just sprouted a third head, but bear with me, because I think that it's not only crude but insightful. "How will this software get my users laid" should be on the minds of anyone writing social software (and these days, almost all software is social software).

IF I had to bet money on any of this being relevant, I'd say (4), (10) and (12) would be the most likely to be so. Facebook just isn't cool anymore. At least not cool for specific niches, like, say, "teenagers" (what teen wants to be on a social-network with his mom and dad, or his geeky little sister, etc?) or college-students ("eeeew, high-school kids!" "eeeeeew, OLD people"), etc.