5 Ways Facebook Could Fail How the giant may be slain By Emily Rauhala, Newser User Posted Jul 25, 2010 5:11 AM CDT 9 comments Comments Five hundred million strong. (AP Photo/Craig Ruttle, File) (Newser) – Facebook, which this week welcomed its 500 millionth user, is the undisputed king of the Internet. But, warns Ryan Singel on Wired, other giants (think: Friendster, Geocities) have fallen. Here are some of Facebook's potential foes: Open Sourcing—New ventures like Diaspora, OneSocialWeb, the Appleseed Project, and WebFinger are experimenting with open-source alternatives. If Zuckerberg keeps invading our privacy, we just might switch. Zuckerberg—The Facebook founder has urged his followers to forsake privacy. But, Singel writes, there could "come a moment where he steps too far ahead, and the flock abandons the frontier for the pasture, leaving him alone and howling in the wilderness." The US Postal Service—What? Yes, really. "There’s always a chance that the world suddenly tires of their Wall and virtual farming and decides to get off the net’s grid entirely." If that happens, we'll need the mailman more than ever. And sockhops. Click here to read Wired's full list. For more on Mark Zuckerberg, click here.