Member Alldarker presents some pretty good evidence that we might see a Rancor pit set in the near future. As you can see in the picture above, there are four 2×2 slots purposely designed into the underside of the new Jabba’s Palace. This, along with the fact that the trapdoor in that set currently doesn’t lead anywhere, strongly suggests that it is designed to fit on top of a rancor pit. You can discuss how plausible this theory is in the 2012 Pictures and Rumors thread.
And if you wish to see more pictures and know more about 9516 Jabba’s Palace, check out Brickmamba’s review of the set.