2. Gotham City Needs a Batman
Ive seen it posed many times in Batman comic lore; Batmans existence inspires high level lunacy in the form of The Joker, Two Face, The Riddler, etc, but when hes in operation standard crime figures are at an all-time low for Gotham City (which is probably still a record high for anywhere else to be fair). With Bruce Wayne leaving Gotham City at the end of TDKR, in my mind, these crime figures would have shot through the roof about 9 minutes after the credits rolled. So with Batman gone, Gordon is left to deal with this new criminal free-for-all alone. Perhaps hes even kidnapped by a group of thugs, who demand the release of their incarcerated brethren in return for the Commissioners life. Cue Batmans return. Of course, upon his reinstatement as the Dark Knight, a new super-villain would emerge to challenge him. Itd be an easy way to reboot Nolans continuity while simultaneously posing Batmans infernal, eternal conundrum: am I actually good for Gotham?