Eventually facebook will become so user hostile the network effect will mean that so many people are leaving it'll be like Digg and Myspace all over again. Can we go back to the time when companies tried to please users instead of advertisers?
For instance businesses need to start evaluating if they really require a Facebook presence. The users that can reach you on Facebook are obnoxious, and expects 24/7 feedback. Unless you are a small niche business you're simply not able to build sufficient community around your Facebook page for it to help further your business. For medium and large companies Facebook is just a place for customers to complain and win prices.
As the company I work for has expanded and become less and less niche we seeing decreasing user engagement from our customers on Facebook, unless they can win a price. At this point marketing really should evaluate the continued need for maintaining a Facebook page, it's just becoming a third support channel, but one where peoples expectations are simply to high, in terms of response time.
Honestly, why is companies like Coca Cola or Volvo on Facebook, it make zero sense when you think about it.