I'm not sure this question warrants a full user story, but the answer greatly influences fundamental interface design.
Are posts made by people, associated with people, and shared with other people?
Are they made in forums? How are those forums structured? How are forums organized? How do you join those forums?
Is it overly presumptuous to say communication is done with posts and thereby asynchronous? Should there be an instant messaging component? Do we pick one or the other, or include both?
Can you search for posts with keywords/hashtags? How important is this concept?
Are there totally novel concepts for content organization we should consider?
I'm not sure this question warrants a full user story, but the answer greatly influences fundamental interface design.