At this stage it’s nothing but an idea. Don’t expect anything to come of it, although there is a chance it might. As it stands, I have no immediate plans to tackle such an endeavor. Besides, the only way I’d have a Batman saga I find truly satisfying would be to make it from scratch, and that’s obviously never happening (besides possibly scripts, but I have my hands full with others already).
That said, I have been toying with ways of tweaking the Joker’s design in TDK to make it more classic.