Doesn't have the Joker. The character is iconic and is a huge draw on his own.
Doesn't have Heath Ledger's death drawing people to the box office. It was a big story at the time and the talk about his performance drew in a lot of people who may have not seen the film otherwise.
I think this film does around 800 mil. Still beating Avengers but not by much.
The fact it doesn't have Joker or Ledger is irrelevant. Why would someone who went to see TDK not see TDKR? The Dark Knight brand is HUGE and that isn't just going to drop off out of nowhere. TDKR will ABSOLUTELY do over $1b worldwide and will gross at least $500m in the US.
The Transformers movies have been shittier and shittier with each successive release but continue to make more money. The only possibility this does worse than TDK is if it's Spiderman 3 bad and there's now way Nolan could put out something that poor.