The problem I see with this is the same problem I saw with Google+. Pretty much everyone who's inclined to sign up for a social network is on Facebook. Seriously, they've got a near 99% market share. In order to get people to move you have to get their friends to move first, and their friends aren't going to move unless they do. Trying to introduce anything that resembles Facebook today is a catch 22, and that's going to remain true going forward. This doesn't change when you're essentially trying to replace Facebook Messenger.
Then again, there's always that one guy who insists on using IRC and hooking into *insert random thing your group is using* through a plugin.