“Many of us primarily read one genre of books, with others sprinkled in. If authors stopped writing that genre, what genre would you start reading? Or would you give up reading completely if you couldn’t read that genre anymore?”
Hum, interesting question! Even though I'm currently obsessed with Urban Fantasy, I don't think I could give up reading just because that genre disappeared. Plus, I tend to be a genre-hopper. My past obsessions include romance (ooh, the trashier, the better), historical romance (yes, I consider that to be a different genre!), cozy mysteries, detective/crime/medical novels (like Kathy Reichs or Patricia Cornwell), and SciFi.
I think I'd head for contemporaries -- possibly adventure and/or mystery -- if my urban fantasies disappeared completely.