Comment by vermilingua

I don't think it can. The AT&T breakup worked, because even then, if you had a phone number, you could contact anyone else with a phone number, even if they weren't an AT&T customer. Facebook, and the other social media silos, are built with anti-compatibility as an explicit goal. That, coupled with Metcalfe's law, means that any upstart will never be able to directly compete with Facebook (or another social network) on it's ground.