I'm in the movie industry. We have strong evidence looking at the past patterns of the harry potter trailers where and when the next one will pop up. I can almost BET my life on this! What is the BIGGEST Warner Brother's movie coming out this year (It will be bigger than Harry Potter)....THE DARK KNIGHT!

Warner Brother's has a habit of promoting their Next big movie on their other Big movie's trailer run. Indiana Jones and Prince Caspian are good guesses but they are not Warner Brother's and they are too far in advanced to start the trailers because the harry potter trailers don't need to come out for long, they already have a HUGE fan base.

Also, Deathly Hallows part 1's trailer will probably come out with...it's a tough one, either Superman: Man of Steel OR The Flash. Deathly Hallows part 2 will come out probably with...Justice League: Mortal.....that one is probably actually my only guess....its yeah it's coming out with that movie, there isn't much else, that's got to be it.