I haven't used Facebook in almost a decade and I haven't missed it for a second. I sometimes ask friends and family why they use it and the answer is always either "I don't know" or "to keep track of friends and family" (AKA: a glorified contact list). Many of them talk about getting rid of it, but few ever follow through.
People love to speculate about "Facebook Killers", but what is there to even kill? Facebook doesn't offer people a useful service. It's just familiar and ubiquitous, so it exists in perpetuity.
> The Facebook Killer will thus be something completely different, not merely a better or more ethical version of contemporary social media.
Then it's not a "Facebook Killer", is it? It would just be another social media platform added to the pile. Just another Twitter, Snapchat, TicTok, etc.