The DCEU can still make a Flashpoint movie with The Flash, and it wouldn't need several movies to set it up. Flashpoint has been associated with a The Flash movie as early as 2017. Possibly the most well-known story on the Scarlett Speedster, Flashpoint carries major implications for the universe at large, making its impact on the DCEU that much more interesting.
2011's Flashpoint comic book miniseries by Geoff Johns and Andy Kubert sent waves across the DC Universe. It was the launching pad for an entire comic reboot, making way for the New 52. The effects of the Flashpoint comic are still felt today, tying in with DC Rebirth and most recently with Doomsday Clock. However, if Flashpoint was adapted for the DCEU, it would look quite different from its comic book counterpart.
Andrés Muschietti has said that his Flash movie, starring Ezra Miller, will be a different version of Flashpoint. This could mean a variety of different things and there are multiple places we can look to when trying to figure out how exactly would a Flashpoint movie work in the current DCEU, which is in a considerably different place than it was when Flashpoint was first mentioned.
The DCEU Is Different Now
To say the DCEU is quite different in 2020 than it was on the first inception would be an understatement. The DCEU began in 2013 with Zack Snyder's Man of Steel., though it didn't really get its start until Batman V Superman: Dawn of Justice in 2016. The plan for the DCEU at the time was a far cry from the cinematic universe concept that Marvel was perfecting. Zack Snyder's DCEU would have been closer to that of Lord of the Rings. But after 2017's Justice League completely destroyed the tightly connected universe, due to Joss Whedon's reshoots and strict mandates from WB, these plans were seemingly abandoned. While the Snyder Cut can still greatly impact the legacy of Snyder's DCEU, Flashpoint would have to work within the current DC on film franchises.
WB has said multiple times that the DCEU will no longer be focusing on the shared cinematic universe concept as a mandate, with directors picking up projects and doing whatever their vision is. An example of this is Matt Reeves rebooting Batman with The Batman or James Gunn's The Suicide Squad being tackled as a reinvention of sorts. For films that have ties to previous DCEU properties like Wonder Woman 1984, Aquaman 2, and Birds of Prey, the emphasis is purely on the titular character and not on an overarching story. Depending on what WB's stance on the DCEU is starting in 2020 will make a huge impact on what a Flashpoint movie can be.
How Flashpoint Can Still Work
There are two primary ways Flashpoint can work for the DCEU. Each path heavily depends on if WB wants to make the DCEU a cohesive universe again or if it rather keeps its characters and worlds separate. In the case of the former, it would make Flashpoint into a Justice League level film. Muschietti has had success with WB, specifically with the IT franchise, and it would not be surprising if they gave him the keys to a story of that magnitude. At the same time, the budget to have Gal Gadot's Wonder Woman, Jason Momoa's Aquaman, Ray Fisher's Cyborg, and Zachary Levi's Shazam appear in the film would be quite high.
Each hero has a substantial role in the Flashpoint story. At the same time, there have been small hints that would suggest something more in the works. Jeffrey Dean Morgan, who played Thomas Wayne in Batman v Superman: Dawn of Justice, has routinely spoken on playing Batman in Flashpoint. In earlier drafts of the film, it might have even been possible, with reports as early as 2016 suggesting Ben Affleck's Batman would appear in the film. Recently, Morgan and Joe Manganiello have dropped teases on social media about potentially being involved in the film. But considering that neither of them have an active role in the DCEU as it is, they might just be having fun with the idea, not that their characters will actually appear in The Flash movie.
The more realistic scenario is Flashpoint will simply be a solo adaption of the story. Andrés Muschietti said that his Flash is a different version of Flashpoint. If fans are expecting a Flashpoint story to closely mirror Geoff John's story, then Muschietti's vision would be different from that. At the core of Flashpoint is the story of Flash and his mother. It is a story that heavily involves characters like Reverse-Flash, his primary antagonist. And so, trimming out the universe-changing aspect of Flashpoint, DC's The Flash movie could easily incorporate the fundamental elements and have Flash create an alternate reality that he can fix at the end. It would then be an emotional journey for him rather than a DCEU reshaping adventure.
CW's The Flash tackled Flashpoint in the Arrowverse. While it did tie into the larger universe, it primarily focused on Flash's own family of characters. It can be assumed that Muschietti's version of Flash can be similar to that. Opting to give larger roles to Iris West or Henry Allen can ease the need for big cameos like Gal Gadot or Jason Momoa. Whether Muschietti has been given the greenlight to go all out on his Flash movie with a budget that can withstand high profile names or is doing a more subdued version of the story, audiences are desperately waiting to see Flash on the big screen.
What Flashpoint Would Mean For DCEU's Future
Depending on how universe-shifting a Flashpoint movie would be, the DCEU will either be standing without change or flip on its head. The most likely scenario is the latter. It can be assumed that the Flashpoint movie audiences will get will be one that is focused on Flash and his family of characters, with not much crossover or DCEU elements tethered to it. In the small case that Flashpoint is closer to that of the comic arc, a few questions could be answered.
With Ben Affleck's exit from the DCEU, the franchise is standing without Batman. Likewise, Superman's future on film, especially with Henry Cavill, is still up in the air. Flashpoint might be a backdoor to explain both. For Batman, Robert Pattinson is now the Dark Knight in Matt Reeves' upcoming trilogy. If WB is confident in the director's vision, they could use Flashpoint to explain the timeline shifting and the multiverse changing.
It would not be a stretch to add a line of dialogue or two saying that events of Flash's timeline has changed and that major events and people will be different when the film concludes, hinting to Pattinson's Batman being retconned in the DCEU. The same can be done if WB is indeed moving away from Cavill's Superman. Regardless of what Andrés Muschietti's Flash film will look like, fans will be happy to see Ezra Miller finally lead his own solo film as Barry Allen.