There's been some talk of the gorilla exhibit, but that's going to still be some time as they are renovating the reptile house and after that, I think they are going to create an Asian section. As for elephants, it always sounds like they are keeping them and are complying to all AZA regulations. I'm still curious if a third elephant is coming, lets hope not, or they were pardoned by the AZA.
Polar bears, Luna and Sakari, are on exhibit together now. From photos and videos I have seen, it looks like they are getting along quite well together.
American alligator Guzman is headed for Florida in preparation for the Reptile House renovations. His exhibit will be replaced with one for Komodo dragons.