Is Facebook fixture or fad? Fortune magazine senior editor David Kirkpatrick thinks it’s the former, so much so that he’s killing his Fast Forward column to devote himself to writing a book about the social network’s influence.

Seems like quite a few of my selected reads have folded up lately. WSJ’s Informed Reader blog shut down early this year, and now Fast Forward’s gone. Good thing the Web’s such a bottomless pit of content.

As for Kirkpatrick’s venture: Frankly, I think he’s one of the ones who’s drunk too much Kool-Aid on the matter. Facebook’s made plenty of noise, and has pumped up its user base accordingly. But will it, or any of the social networks, last long enough to effect deeper changes in how people communicate and collaborate? Loyalties to online turf are pretty thin, and fickleness emerges whenever even superficial changes are implemented (especially commercially-motivated ones). Portal websites like Yahoo!, Excite and the like were once the great aggregators of online eyeballs, and they dropped off after a short time. I’m not convinced that these latest walled-garden sites will fare any better in the long run.