I was thinking about this yesterday and in other threads people are writing about similar systems. The key thing for me and the word that keeps getting written is "RSS", I want a powerful client to experience different content in different ways. There are many communities and content creators that I want to follow but it's too complicated with modern platforms. From a usability standpoint it's bad both for creators and for end users, the result of this is that you miss out on some important stuff.
For example I might not have time to watch Twitch streams or Youtube videos from a creator over a couple months but I would still be able to go to a weekend event in my city or buy some some new merch that he announced. In general I would need to use another platform to not miss out (Twitter, Instagram).
If I controlled a client capable of aggregating all types of content I could decide to filter things out according to my immediate needs.
Content creators would own their own platform or choose a generic service provider and have freedom about what to make (video, image or text posts) and how to monetize.
The problems are who pays who, content discovery, and a decently sized userbase.