Ahahaha I am actually writing a research paper on fandom right now, but not about that. (It's a pretty basic paper, outlining how writing stories in the context of the fan community produces a totally different type of writing. I get to throw the word hypertext around.)

I actually think the new successor to serial mailing-list fic is commentfic, especially on kinkmemes. It's that same open-ended feeling. (Now I'm wondering if LJ introducing the stalkerpin tracking tool prompted the rise of commentfic, because I know it changed how I read them.)

sounds like nothing so much as the definition of a soap opera

And that's really interesting, because one of the books I'm reading for this research paper talks about how soap operas are about telling the same story over and over, with lots of repetition and never a real ending, and that's actually a pretty good description for fandom.

And to your ETA: And this is why I love my WIP tag. :D