I don't use TikTok, so I'm probably wrong here.. but isn't TikTok "algorithmically served user generated content" rather than "community" or "social media". As I understand it, it's like a TV station. If there's "dialog", it's in the form of answer-films, rather than actual discussion. If it does behave the way I think it does, then it backs up the idea that social media is on the wane.
TikTok can be considered at least 3rd generation, if FB and Twitter were second and first is MySpace. I am sure one could argue there are more generations. Twitter is not among the first social media god generation.