You can now do a single-click login from Facebook on Gothic BC. If you have and existing account, you should log in normally first and make sure that the e-mail you have registered for Gothic BC is the same as the one you used to register for facebook.
So the "exodus" to Ello is the big deal du jour. Right now, it all bears a striking resemblance to the initial scramble to Google+ that still hasn't really gained traction. There's no real way of knowing at this point.
An article in the Vancouver Sun today reveals that a study funded by the European Union has found that Facebook is "not just on the slide, it is basically dead and buried".