We could assume that the Nolan-brothers were lying when they wrote in the script that Harvey's dead, in order to let people believe that he's dead and because of that we won't figure it out that Harvey's gonna be tha main villain in Batman 3... but I don't think that's likely.
And I also believe that in the Nolan-Batman-universe, where everything is so realistic, the emotions, the motivations of the characters and everything, Two-Face can't be a main villain, who makes plans to take down Batman and Gotham. In the Nolan-universe Two-Face is only an insane man, who lost his love, and because of that he grabs a gun and shots a couple of man. Two-Face CAN'T be more in a Nolan-adapted Batman-movie. It would be... surrealistic. (like in Batman Forever)
- He's clearly dead according to the script (not my argument, but a general one that people use).
- Dead according to Chritopher Nolan (director), Jonathan Nolan (writer) and Aaron Eckhart (Harvey Dent/Two-Face himself).
- No reason either thematically or plot-wise that he needs to be alive.
- Severely weakened condition AND he fell almost 5 stories.
- The film's ending is nowhere near as impactful is he's alive.
- He would have died anyway (from infection or being gunned down by police).
I honestly don't know why we're still arguing about this.