It's a chicken and egg problem. Without users, a new social platform lacks content, so it can't attract users. Unless something decidedly new and compelling comes along, users will probably stick with what they know... unless something happens that really pisses them off.

If I'm being honest though, I don't think privacy concerns will be what does it. The TikTok generation doesn't give a fig about privacy. You can build a panopticon around them and they won't even notice.