According to CHUD, Aaron Eckhart will not be returning to the Batman film series.  They recently spoke with Eckhart, and when asking him about the role of Harvey Dent, he said, "He's dead".

Eckhart say that he has asked Christopher Nolan about a possible return of Two Face and the director gave him the same answer. 'No way,' Nolan said. 'He's toast.'"