If he was still alive yes, I would imagine he would be an ongoing character. From the sounds of it originally he was going to be in both the dark knight and its sequel, but alas. It must have been extremely difficult for Nolan to figure out what he is going to do next. My sugestion for all those hoping for your fan favorites to appear in the next Batman is ask yourself "do they fit?", "would it be contributing to the story?", "how does it move the characters along?", "how would they be introduced?", "were there hints in the last movie?", "does this character stem from a cold plotline?", "if this were a stand-alone movie, would the introduction to this character make much sense, or would I have to be an expert on this series, or Batman in general?"