Heath Ledger’s death did give TDK a boost in terms of publicity, but there was plenty of buzz for it before that. The movie was made largely because WB was impressed by how well Begins performed on DVD, and there was a pretty strong viral marketing campaign in the months before Ledger died. In any case, TDK was a big hit and the most talked about movie of the year, so it firmly cemented that Batman was back in full force at that point.