I would say that a "prestige product" like the Dragonlance set or the Deck of Many Things set around the holidays would be most likely. I really can't see a slip-case simply because (a) there's not much call for a full bestiary book (there are very few FR-specific monsters that haven't been covered elsewhere - the phaerimm, sharn, and deepspawn are really the only important ones that haven't been done) and (b) there's no need for a FR-specific adventure as well... we have a whole lot of them already! So, basically a 196 - 224 page setting book (maybe more if we're lucky), plus... something(s) else like the game in the DL set or the card set with the BoMT set. The music could be part of it, but I doubt all of it. I'd love it if we got a whole bunch of Schley maps, for example. The setting book would still be available separately for those who don't want the extra bells and whistles.