1. Open Endings Leave Infinite Possibilities
The creative decision to leave the end of The Dark Knight Rises open - in terms of the suggestion of John Blake's fate chiefly - and to only really partly resolve Bruce Wayne's story has left Warner Bros with a raft of possibilities to continue. Though the film was suggested to be a full-stop on the end of the trilogy, tying up ends and resolving key issues, the final sequence left a lot of unanswered questions, and even more unexplored possibilities, and the idea that Warners are happy to leave all of those branches to die as shoots seems an almighty waste. Had Nolan tied up more, and not consciously decided to imply continuity beyond the boundaries of his own trilogy, this wouldn't have been the case, and it is conceivable that the director made that choice as a nod towards the alinear nature of traditional comic book narrative arcs, but the rest of the films were so intentionally non-comic book in nature that the open strands of the ending demand further exploration. In essence, because Nolan promised finality, but then teased at a whole new beginning for Batman, it would be a massive missed opportunity if someone wasn't brought in to at least explore those possibilities. And in purely narrative terms, the state of Gotham by the end of the movie is enough of a draw to continue this story strand, given how major a plot-hole it would be for the book to be closed on Gotham with the city in ruins. More of which later...