A lot of people find certain features of facebook really useful (e.g. organizing events), and there are still groups of people almost exclusively using facebook

A lot of people find certain features of facebook really useful (e.g. organizing events), and there are still groups of people almost exclusively using facebook chat. Just because people are still using facebook doesn't mean they trust facebook with private data. Even my mother uses facebook, but she absolutely refuses to put anything even remotely private on facebook because she assumes facebook will snoop it. So even if it turns out that facebook is selling off all of its data to the highest bidder people would probably still use it, unless there is an alternative. For chat we're seeing more and more protocols and apps springing up, both proprietary and open source - e.g. XMPP or the much younger/newer http://matrix.org http://matrix.org (which I work on). For event organization? The key thing that makes facebook useful for this is that pretty much everyone has an account. You could probably build something on top of a distributed/federated chat/data replication system (like Matrix or possibly XMPP, etc.), but I don't see any new closed app being able to get enough traction to overthrow Facebook there.