What then, would Facebook be if it wasn't Facebook? With the currencies of 700 billion minutes a month and the emotional investment of all those users, here are some other companies whose business model Facebook could easily adopt, overtake, or buy:
Shutterfly - Facebookers love pictures. It's not a far leap for Facebook to offer a picture service that creates albums and mails printed pictures to you. What's the need for a somewhat redundant Shutterfly account?
LinkedIn - There are those that feel that Facebook should be mostly personal rather than business focused, like LinkedIn. More and more though, business and personal overlap. To quote Sir Richard Branson "I don't think of work as work and play as play. It's all living." Building a business channel would make Facebook even more influential then it is today.
Twitter - Please don't misunderstand, hash tags put me in a command prompt (and New York?) state of mind. But for me, a tweet and status update meet in Hootsuite. Again, why the need for redundancy? Especially if there is a "Facebook for Business" stream in the future. Perhaps status updates and tweets will meld into a "stweet?"
WordPress - At its core, Facebook, like WordPress, manages content. If I have a potential network of 500 million users I could publish AND target to, why would I go anywhere else to peddle my content?
Meetup - The new Facebook Groups functionality allows for a closed group within Facebook's already closed network. Communal activities done on Facebook will soon be coupled (and in a less organized sense, already are) with invites for offline group activities.
Once Facebook Convergence is complete, what killer apps outside of Facebook will be left?
Think about your current social media campaigns, today. Think about how they might change if even one of the above suggestions occurs...