Gary Kubiak is an offensive coordinator that has NEVER called the plays for his offense. Just because he has the title of offensive coordinator for the Broncos doesn't make him a prime head coaching candidate. There is a reason he hasn't gotten any offers to date. It's the same reason Sherm Lewis didn't get any offers. They simply don't have enough input into game situations than their title would lead you to believe. Kubiak is basically a quarterback's coach that has the title of offensive coordinator.
I don't think Wannstedt should be fired, but if he were to be fired, I'd go after a guy like Maurice Carthon. The reason I'd target him is because he will come in and keep the philosophy of playing defense, running the football, and winning in the kicking game. I don't want to see a dink, dink, dunk offense like the West Coast offense in Miami. I want to see Miami blow people off the line, run smash mouth football, and throw it deep off the play action.