It might survive in the manner Digg survived.
Digg didn't survive though. Right now it looks like a corporate blog with a barely visible comment section.
That being said I think Reddit will likely survive better than Digg or MySpace (if only as a shell of itself) due to having more "normie" users, especially when outrage subs like politics and wpt have conspicuously not gone private.
really isn't wise in a lot of ways when thinking about how people usually use facebook. imagine if you and your grandma's instances defederated from each other.