I haven't read this entire thread and don't know what all information has been released about the film, so correct me if I'm wrong - but isn't all this speculation that the film's story will hinge on Bane exposing Harvey come from a single still of Bane holding up Harvey Dent's picture before a crowd?
If so, that seems thin evidence upon which to decide that the main blow Bane deals to Gotham is destroying Dent's reputation. Especially since Hardy has spoken about Bane primarily in physical terms -that's he's wildly brutal. Seems more likely to me that he'll sow terror by randomly beating the hell out of people and anything having to do with Dent will be relatively minor - adding insult to injury essentially.
But maybe you all know something I don't so I could be wrong.