Sorkin didn’t get specific about whether the discussions with DC or Marvel involves work somehow with their comic book libraries, or if his involvement would be tied to the DCEU or MCU.
Bringing a character-oriented screenwriter like Sorkin on-board to help translate stories from the character-oriented medium of comic books could make for a unique package.
Whether it be Warner Bros. with DC, or Disney, Columbia or Fox with Marvel, studios are all too aware the danger of material becoming too stale, especially if their productions lean too heavy on visual effects.
As a heralded scripter of film and television dialogue, and given the increasing output from both the DCEU and MCU in both venues, the latter seems to make the most sense.