Most corporate social media companies convert to a system of content creators that earn a living off their work, either as direct compensation from the company or via embedded ads. Non-professional participation is usually through this lens.
To keep users on the system, private networks are developed and expanded. Private chats and discords develop to full on forums.
Federated networks are out there, but it isn’t the default. A lot of it is based on specific fandoms. Likely, this is funded with donations, which starts being problematic as communities become dependent on a set of benefactors.