I think the minute that Primal has private group feeds that work well across multiple major Nostr apps, none of the corporate social media platforms will stand a chance. I have MANY friends who are interested, but are turned off by the global visibility of everything they post. We have 1:1 Messages, but what we need are group messaging that is secure from anyone outside the designated list of viewers.
Most people are leaving FB, X and others looking for a place to talk to their friends, their tribe, their circle.  As soon as Nostr can deliver on that, everything else will collapse and go completely ghost town.