This video from LibrePlanet gives quite a good summary of the fediverse in 2020, what it is and a rough guide to how to get started on it. It also discusses the advantages and disadvantages to self-hosting an instance.
The fediverse has been around for 12 years, but it was only after 2016 that it started to gain any significant amount of popularity. Now I think it's safe to say that it will stick around for the foreseeable future, or for as long as http and json remains relevant. The federated model seems to be the current best arrangement for social interaction, which avoids the global censorship of walled gardens but also allows communities to set their own moderation rules so that they don't dissolve into pure entropy.