Warner Bros. never really had a plan for the DC Extended Universe, which became evident when Batman v Superman: Dawn of Justice and Justice League writer Chris Terrio recently explained that he was forced to write those movies without ever being clued into plans for characters like Aquaman and Wonder Woman.
Despite that, we know Zack Snyder had loose plans for a "five-part trilogy" encompassing the two movies listed above, Man of Steel, and a couple of Justice League sequels.
Talking during this past weekend's Justice Con, DCEU storyboard artist Jay Olivia revealed that there was an endgame for the SnyderVerse with a Flashpoint-style reboot hitting the reset button on this shared world. That would have then allowed Warner Bros. to recast some key characters.
"I think that was the plan was that they would do like the four or five parters, and then we would do a Flashpoint kind of reboot, where you can bring in a new cast afterwards," he explained.
This is the first time we've heard this, and it's unclear whether this reboot of the DCEU was the original plan for The Flash movie. That would make sense, especially as there was no indication that Snyder planned to include this in Justice League 3 (instead, that was going to end with a flashforward revealing that Clark Kent and Lois Lane's son became Gotham City's new Batman).
It's hard to believe that any of this will play out on screen now, but Andy Muschietti's version of The Flash could serve a similar purpose, helping the DCEU move on from Snyder's vision.