One of Mark Zuckerberg's goals is to make Facebook's News Feed a "perfect personalized newspaper" for every user. To do this, the News Feed algorithm attempts to show users the updates, birthdays, events and shared stories that it thinks would be most important to them. It follows that news sites have been very successful under this system.
In fact, with so many news sites getting more and more referral traffic from Facebook, the network's influence has never been more powerful. But what will happen when they finally decide to directly host content instead of having publishers post a link? We're about to find out.