Well, IMO, an artist shouldn't look at their previous works when doing something new anyway and what I'm trying to say is that if you look at Nolan's films he never tries to "top" himself on anything. There's a movie told backwards, a weird hybrid of fantasy and sci-fi, a thriller, an action/adventure movie and a crime/action flick. Even between his Batman movies there's no point of comparison. He hasn't tried to top anything, because he never does the same thing twice. If you do continually try to "top" what you did last, it means you're trying to improve on a past work and your style just ends up derivative. I don't think Nolan's ever going to suffer from that because he's been super-smart in what he does and does not do.
Therefore he's under no obligation to return to "top" what he did last because Nolan will not make another film like TDK again. If he returns for Batman 3 the film will not be the same as TDK, just as TDK was nothing like BB. Aside from using the same characters, there's not a lot of similarity between the two pictures.
Nolan will return if he finds a story that he can explore something new. These thoughts of "topping The Joker" and all that aren't thoughts that will enter Chris Nolan's mind. I agree to a certain extent that Nolan will return if he can make a better movie (he has said this himself anyway) but the phrase "top" implies that Nolan will look to TDK to discover what he can do better and this will certainly not be the case.
If there's one thing you'll learn about Chris Nolan it's that he's 100% sure about what he puts up on that screen. That's why we never get deleted scenes, that's why we never get director's cuts. What is in Nolan's cut is what he thinks is perfect.
Oh I agree about him changing it up. You're constantly changing styles, adopting a new project, tweaking things here and there. I agree with you in the aspect that, if Nolan returns, we will most likely get a film as different from TDK as TDK was from BB.
However, this is all more of the same process of trying to better yourself. As an artist you are always striving to make your next product better than your last. However, I think you're misinterpreting what I, and others mean by this. Wanting to always better your product doesn't mean looking at a past project and going "how can I do that same thing again...only better?"
Part of the creative process is trying new things, incorporating new ideas into your work, but always with the mind of trying to make whatever you're working on the best thing you've done. I'm sure Nolan will look at individual things he did in TDK and think "I know how I can take that idea and do it better," but he's not going to come in with the idea of making the same style of movie, but trying to top it.
He's going to try and top TDK, but to him, "topping" it is making a film as new, different, and exciting as TDK was. This is why we see such a wide range of ideas and styles in all of Nolan's movies, because he's constantly trying to better himself, to top what he did, and that will force you to explore different and new ideas.
I think you're getting the idea that when we say "top" we mean it in the Micheal Bay sense of "my last movie was good, so for the next one I'll add more explosions and hott women!"
That's not trying to top yourself, that's just doing the same thing you've already done, but just adding more of what you already had in the previous movie.
