...fans can choose the categories they want to put on their pages...

If this is the line that the committee is taking, then doesn't it in a sense make the whole issue about how to categorize anime/manga fandoms rather simple? Some fandoms could use the old "Format" categories and some could use "Fandom by Source Community" categories and some could use both, depending on what suits the users/fans best.

I suppose I'm confused about where the line is drawn between top-down and bottom-up decisions about how the wiki is supposed to operate.