We never saw any actual funeral for Dent in THE DARK KNIGHT. We see either Batman or Gordon's vision of the near future, the Dent tribute, the smashing of the Batsignal, then it cuts back to Batman running from the crime scene. It's no more set in stone than the end of BATMAN BEGINS was...did DARK KNIGHT open with Batman investigating the Joker hours/days/weeks after his meeting with Gordon? Nope.
But really, they should go with my ideas. Dick Grayson will be a kid hit by a bus. Selina Kyle the name of a murdered prostitute. A bird shop named Cobblepot's and its fat owner will blow up in an explosion.
Bane will be a wrestler glimpsed on t.v. for 2 seconds. Mr. Freeze will appear...on the side of an Ice Cream truck.
The villain of the movie will actually be Tuttle King, the new mayor of Gotham...nicknamed by the media KING TUT.
Or have a paroled/escaped Carmine Falcone be the mastermind villain, with somewhat eccentric hitmen after Bats...like THE PUNISHER (2004) where Castle the fought the guitar guy and the Russian.