What enemies do you think will be in Halo 4?

Considering how anticipated this game is becoming, what other enemies do you think we will be seeing in Halo 4? We already know bare-armed Elites can Grunts with exposed mouths will appears, and even some concept art with Jackals in the distance, but we do know that the flood is now canned. Getting on topic, I think we will be seeing the return of Sentinels, considering Requiem is a Forerunner Shield World, and Sentinels were present on Onyx, another Shield World.