What Would A True The Dark Knight Sequel Have Looked Like?
2. Blake And Selina, But Probably No Bane
With Dent killed, there would have been room for another law enforcement character in the Dark Knight sequel, and it's reasonable to assume that Joseph Gordon-Levitt's John Blake, or someone very similar, would have made it into the movie either way. Even without such a big time jump, even without Bane, Blake is important thematically to the character of Batman and what he represents. If they're to keep the same ending, then he would have to remain too.
The other roles likely to have been in are Selina Kyle and Talisa al Ghul, or at least one of the two. With Rachel dead there's an obvious vacancy for a female lead, which Kyle can step into easily and provide some antagonism for Bats before their eventual team-up.
Talisa is less certain, but the movie could do with another villain, and she would help Nolan connect things back to the first movie in a way that feels natural, but in a movie that also doesn't ignore The Dark Knight too. Bane, however, might have to fall by the wayside: Nolan chose him because he's the complete opposite of Joker, looking for order where the other seeks chaos, and it's hard to imagine how the two would co-exist within the same movie.