The next Batman movie is set outside of the DCEU for now, as Matt Reeves (Dawn of the Planet of the Apes) is making a new movie about the early career of the Caped Crusader titled The Batman. Reeves already shook up the fanbase by casting Robert Pattinson as Batman, something that many fans can't get over, due to his early roles in The Twilight Saga.
Reeves also said that he is not making this movie inside the DCEU because he wanted to tell his own story without having his hands tied by other movies tying in. However, with the news that The Flash will introduce movie fans to the Multiverse, that does not mean it will never tie into the DCEU.
Straight up, the biggest reason that The Batman should join the DCEU in the future is because of the Multiverse. In The Flash movie, there will be at least two Batmans in the film, including Ben Affleck and Michael Keaton. There will be other Earths, and it would be amazing to see some old names return, whether it is George Clooney, Christian Bale, or even a new name like Robert Pattinson. Even if it is just fan service, showing that Pattinson's Batman exists in the DCEU, even if it is on an Earth that will never connect to ours again, would be very cool.
There is one perfect reason not to join the DCEU for Matt Reeves' Batman movie. There is no reason for it to connect to the overall world of the DCEU, even if as part of the Multiverse. If it is never shown as part, and never connects in any way on the big screen, that doesn't mean anything when it comes to fans.
If there is one thing comic fans love more than watching a movie, it is debating it or coming up with fan theories. The Batman could never appear in the DCEU, and there would still be fans who believe it is part. For those who don't want it there, they never have to have those theories proven. Everyone wins.
The Flash is telling the story of Flashpoint. While Michael Keaton and Ben Affleck are both going to be in the movie playing different Batmans from different Earths. That is all we know so far. However, Robert Pattinson showing up could open up even more Earths. One thing that the Multiverse promises is that there is no one method of storytelling. Having a darker Batman on another Earth could open things up for Barry Allen as he and Warner Bros. start to rebuild the DCEU.
If there is one complaint that several fans and critics had about the Zack Snyder DC movies, it was that they were too dark and brooding. Even Superman moped around and never seemed like the Man of Tomorrow from the comic books. Batman, on the other hand, has never needed optimism.
However, as the DCEU changes on the big screen, things are lightening up and becoming something kids can enjoy as well. Wonder Woman and Shazam! prove that Warner Bros. wants to sell its superheroes to all members of the family. This version of The Batman needs to be dark, and that means disconnecting from the DCEU.
If Robert Pattinson's Batman shows up in The Flash movie, it could be a colossal marketing moment for Warner Bros. Knowing this specific Batman could play a role could help sell the upcoming Flash movie to fans who might have loved the more adult Batman story Reeves presents. The DCEU needs all the goodwill it can get. Likewise, people who might have passed on The Batman might go back to check it out if he shows up in The Flash, knowing they connect.
No one can deny the fact that the DCEU is tainted. This is because the recent changes made with Justice League split the fanbase down the middle. The fans and critics who always complained about the darkness of Snyder's version of the characters and the fans who demanded the darker Snyder Cut clashed, and there was no way to satisfy both groups. Adding a movie like The Batman, especially with its bold casting decisions, didn't need the baggage of the DCEU pulling it down.
Joker proved one big thing when he appeared in his solo movie, separate from the DCEU. Some heroes don't need to be part of the overall extended universe to remain successful. Joker picked up Oscar nominations, and Joaquin Phoenix was a revelation as the Clown Prince of Crime.
However, not putting Robert Pattinson's Batman in the same world as Phoenix's Joker would be a huge misstep. Adding the Batman and Joker to the Multiverse could add these two movies into the same overall world, and who wouldn't want to see these two actors meeting up down the line?
The biggest reason not to have The Batman added to the DCEU is that Matt Reeves didn't want the movie as part of it. That doesn't mean it world can't be added in down the line, but for now, it would be smart for Warner Bros. to honor their directors' wishes. This was also confirmed for the movie at the DC FanDome 2020 event, where producer Walter Hamada said that The Batman would be more grounded than anything fans have seen so far from DC.
There is something to be said about big event movies. When Marvel released Avengers: Endgame, it shattered many records because people flooded to theaters to see all the heroes teaming up in one big film to battle a giant threat. Nothing was bigger in the Arrowverse world than the crossovers each year, especially when Crisis on Infinite Earths rolled around. Warner Bros. would be shortsighted to not see some significant crossover event with all its movies in the future, The Batman included.
The main reason to slow down any talk of bringing in The Batman to the DCEU is that this isn't Marvel, and it isn't The CW. This is the DC Extended Universe, and right now it is a mess. Fans have shown confusion at many decisions made by Warner Bros. concerning DC, including the new upcoming Snyder Cut release. Until Warner Bros. gets its own house in order pertaining to the DCEU, they need to keep these prestige superhero films out of the mess they created.
