As I recall, the six books thing was always just a rumor. Heck, they've got practically that many in production for the Buffy game, with Buffy Revised, Welcome to Sunnydale, the Investigator's Handbook (Angel), Tea and Crossbows (Buffy/Angel), Encyclopedia Demonica (Angel), Lawyers, Gods and Money (Angel) and Military Monster Squad coming. And there's been unconfirmed reports that they'll be given the green light to do post-finale books in the same semi-continuity as the novels like "Queen of the Slayers."