WB/DC already has THREE on-going/upcoming cinematic Bat-verses…
- Joker / Joker: Folie a Deux
- The Batman / The Penguin (TV) / The Batman Part II
- The Brave and the Bold / Arkham (TV) (both upcoming DCU release)
Even if they wanted a fourth, Nolan has said emphatically that he's done, that Bale's Batman story is over (rumor has it WB offered him $50M to return for Batman v Superman and he turned them down), and that Robin took over Batman's duties in that universe.
Nolan also just made a billion-dollar-grossing R-rated period biopic that's about to win Best Picture, for which he'll likely also win Best Director. In other words, he's in rarified air, at the absolute peak of his powers. Especially after this, there's no chance in hell he returns to the world of superheroes.