I only saw 3/4s of the movie, so I didn't catch the Joker cameo.
(if it was in the beginning)
Anyways, I still stand by my opinion. After TDK, Joker was to big to only have a cameo for the sequel. Bane might have second thoughts of releasing Joker, but he'll release him. Maybe thinking he could control him. Joker takes Bane's plans and turns it on itself. Then a final confrontation with Batman.
If Heath was alive, TDKR would be a vastly different movie. I see it as Batman vs Bane vs Joker