Matt Reeves’ The Batman movie was previously featuring Ben Affleck as the World’s Greatest Detective. Affleck played Batman and Bruce Wayne in two DCEU (DC Extended Universe) movies: Batman vs. Superman: Dawn of Justice and Justice League.
Affleck would be hanging up the cape and cowl for the solo Batman movie but is credited as producer. He could be potentially replaced by Oscar Isaac in the bat-suit.
Oscar Isaac was last seen in Star Wars Episode 8 and he was quite impressive. Whether he could pull off the Caped Crusader is another thing, he could play a brooding and dark hero. After Christian Bale, Michael Keaton and Val Kilmer impressing in the cape and cowl, Isaac would need to fill in huge shows.
Affleck was also a fine Batman given the script of the two movies he played the role in. So far, Michael Keaton and Ben Affleck are the only two actors to play Batman in two successive movies respectively.
Christian Bale starred in the Christoper Nolan Dark Knight trilogy. Val Kilmer and George Clooney only took on the role once respectively, with the former’s movie, Batman Forever, being a huge hit and the latter, Batman and Robin, critically panned.
Oscar Isaac is going to be appearing in the next Star Wars movie as well. Right now, his potential starring role as Batman is only a rumor so we should take it with a pinch of salt. Nothing is confirmed of it as yet. Another rumor that the new Batman movie would be more close to Frank Miller’s Batman: Year One. Our fingers are crossed as in who will be the next Dark Knight. Until then, we can look forward to Aquaman later this year.