Facebook will die.
When it comes to asserting my regard for Facebook's prospects I feel a bit like the guys over at housepricecrash.co.uk. This website was set up by friends with a mutual interest in the UK property market in 2003 and, as the name of the site subtly betrays, they predicted a bit of a tumble in house prices. And of course they were proved right. Eventually!
But social networks aren't subject to the same dynamics as the 'irrational exuberance' that fueled the house price climb to an all-time high. In the arena of social networks it comes down to a mix of 'softer' issues, such as the simple push and pull of fashion, and 'harder' issues, such as the underlying technological construct of a social network.
Economics can take a role, most obviously at play with the so-called 'network effect' eBay concreted in many markets, and in their ceding some markets to Yahoo! for example where Yahoo! secured that market's network effect first. But that's more ecommerce than social networking. Read more