That's odd to have that continuity break since everyone else is returning. This, to me, means we're probably going to see:
spoiler (click to show/hide)
Her character die and probably NOT a lot of screen time. Goyer and Nolan confirmed that Dent and even Gordon will want to kill the Joker by the end of the movie, but Batman prevents that from happening and has to live with the decision when Joker burns Dent turning him Two Face. My guess is the only reason why a guy like Dent and even Gordon would want to see Joker killed is if he murdered someone they knew, and imagine how much that would suck for Wayne if the only voice of reason is the only one who was romantically involved.
Yeah, word is:
spoiler (click to show/hide)
He's going to be taking the caretaker and underworld liaison for Roman Sionis' company, who is supposed to be the antithesis of Bruce Wayne and make Wayne's personal/business life hell. Sionis is apparently caught up in deals (my guess is arms deals, from what has been circulating) between Thorpe/Maroni (I don't they've decided on the name of this character, yet) and the Penguin (Bob Hoskins, please!). The Joker, who has been described as an anarchist by crew and director, pretty much screws all of this up somehow. I kind of like how Bruce Wayne has dual lives and both come under attack at the same time.
That said, if they keep Dawes' character, he'll also have to juggle a romantic life, plus there will need to be new characters or plot elements introduced for Gordon and Dent to be push to murder. Gordon already has a relationship with Dawes, and it's logical that she'd share one with Dent since they're in the same office, so I think that's the best use of the character.
If they really want to torture Wayne, they could write that Dawes is set to marry Dent, even.
I refuse to believe she was "acting" in Secretary or Mona Lisa Smile.
spoiler (click to show/hide)
Yes, I was forced to watch the latter. :'(