Looks like Ben Affleck is not done with Batman as originally reported. He will star in the Matt Reeves Trilogy which will lead into Batman Beyond.
Terry McGinnis started out in the cartoon Batman Beyond, where he takes over the mantle of Batman from an old Bruce Wayne. He first appears in comic form in Batman Beyond #1 (1999). His first proper DCU appearance is in Superman Batman Annual #4 If they do Tim Drake Batman Beyond, his first appearance is New 52 Futures End #2
“According to a Warner Bros. source Ben Affleck has signed on to appear as the Batman in Matt Reeves Trilogy. Affleck will play the Dark Knight for three more films, with the last leading into a Batman Beyond film, which will also lead to the next phase of the DC Extended Universe.”