However, Facebook has some things going for it that ICQ didn't. for example:
Grandmothers - Facebook started with the early adopters just like everyone else. But they slowly moved (and are still moving) down the curve, past the 'what's a browser' middle and down to the users for whom email is a big challenge. People who basically don't use computers except for occasional tasks that someone else has shown them how to do and set everything up. These people don't switch easily.
What's going to kill Facebook is something better. Less spam, better privacy, etc, but it still needs to be at least as good as Facebook to get anywhere. And that’s going to take a seriously long runway a great development team and awesome management. Look for a profitable nitch like LinkedIn that just keeps growing.
Grandmothers won't save Facebook. They'll allow Facebook to linger on like a maladapted dinosaur or the old VAX your IT department uses as shelf space. But in a post-Facebook world, just because we all keep Facebook accounts to maintain ossified relationships doesn't mean Zuck still has social relevance.
My fiancée and I are in our late 20s. We were in college when Facebook came out and arrived at the party early. We built our social networks to share the fruits of our newfound "adult" freedoms- namely pictures of inappropriate Halloween costumes and drinking games.
Now, Facebook is different. My mom is on it. My mother-in-law-to-be is on it. But because my fiancée and I are on it, our children likely won't be. It won't be a fun place to share things you don't want mom to know. Mom will be checking in and leaving embarrassing messages on your wall. I think my kids will probably find somewhere else to hang out. It will probably have a name I can't seem to remember, and I will likely embarrass them in front of their friends by pronouncing it wrong or misunderstanding its key features.
Social networks are binding, but they're highly generational. Unless Facebook can figure out how to get my future kids to think its cool, it's toast in 20 years or less.
--Edited for grammar--
Already I see awkward parent/child relationships. To the parent, they love feeling 'in touch'. To the child, it's just embarassing that their parents are hanging around on Facebook. As they move into the embarrassing photos/stories, they're either going to find a new platform or create a separate identity, or something, to conduct themselves online in private.
SMS was the killer app for teens because they could exchange messages with friends (a) cheaply and (b) without being overheard.
If I found a new social network that I thought offered something new I would start using that in parallel to facebook. Then I'd use the new one more as more people moved over, until eventually facebook just became a way of emailing my grandma.
A lot of these facebook killer conversations seem to be based on the idea that I'm only going to use one social network. I'd argue that's not true at all.
Facebook has 500+ mil users. Most of them, non techies.
Friendster actually proves my point...they shot themselves in the foot. Facebook exists because of mismanagement by Friendster.