Don't fall into that trap: it's dangerous. Twelve years ago AOL was doing just as well ($1-2 billion each quarter, $300-400 million in earnings), and was the largest portal/ISP around. Blackberry and Nokia were kings of the mobile mountain five years ago.

You are only as good as your current product: Facebook's commodity is people, and people are not as loyal as you might think.

Facebook could very well be around a long time, but 'forever and ever and ever'? Smart people have lost a lot of money thinking like that. I certainly wouldn't gamble on it.