It could be called "iMessage Social" or something like that. The basic premise of the app would be basically an extension of iMessage to include a social aspect. The app would be limited to iPhone users as they're already authenticated by Apple offering the privacy and security Apple is known for. The app can be used to create groups/events with other iPhone users, discover trending news, topics, sports etc. using Apple Intelligence. You have a profile that you can choose to keep "Private" (only your contacts can follow you) or "Public" (other authenticated iPhone users globally can follow you, read your posts, view your photos etc).
In a nutshell, it'll be a Twitter-like iMessage social app but you know that you're conversing with an actual person since its backed by Apple's privacy and security promise, no bots or ads. Apple will essentially be using their global network of iPhones to make this feature work.
What do you think? Would you use it? Any other features you'd like to see? Is it viable and do you see Apple making something like this?