Snyder Had a Finite Arc Planned
The irony of this situation is Zack Snyder never planned to make a sprawling shared universe. His DC movies were supposed to be self-contained, and that arc could have been coming to a close this year. Justice League 2 was given a June 14, 2019 release date, and could have marked the end of Zack Snyder's DCEU. Snyder planned a 5-part story centering on Superman, but it went back and forth between 4 and 5 movies as things changed behind the scenes. With Warner Bros. losing patience with Snyder's movies, it makes sense that they would opt to bring things to a close with Justice League 2 (cutting or comgining it with Justice League 3), paving the way for a total reboot.
Snyder's goal wasn't to build something more like Christopher Nolan's Batman trilogy, albeit a little bigger due to spin-offs and more characters. Like Nolan's Batman trilogy coming to a close before Man of Steel arrived and the subsequent casting of Ben Affleck as Batman, the DCEU would have had a similar conclusion.
Ben Affleck, for example, never signed on to be DC's Robert Downey Jr. or Hugh Jackman with plans to play the role for a decade or more. He was sold on a short run as Batman, ending with the caped crusader's sacrifice. His arc would have started in 2016's Batman v Superman: Dawn of Justice and likely ended in 2019's Justice League 2, with The Batman happening in the middle along with some cameos, like his appearance in Suicide Squad.
Zack Snyder's DCEU Could Have Been Rebooted Naturally After 2019 Anyway
Once Snyder's planned arc was completed, Warner Bros. would have had a clean path to transition into a new continuity with no loose ends from Snyder. Whether that's through a Flashpoint style reboot, as was on the slate at one point, or some other mechanism, WB would have had the opportunity they wanted to have a clean break and move away from Snyder without the drama surrounding his exit, a failure of a Justice League movie, calls for a Snyder Cut, and the general lack of direction in the post-Justice League universe.
So now, we find ourselves in 2019, about to lose a 4th member of Snyder's original Justice League cast, and with little to show for it. While public perception of the universe and excitement for the future slate is finally improving, the route to this point has been anything but clean. Simply allowing Snyder to complete Justice League as intended and making Justice League 2 the endpoint of his saga would have avoided the chaos following Justice League, given them a chance to properly set up a reboot, and given Warner Bros. a couple extra years to plan a proper relaunch instead of trying to bootstrap a new cinematic universe on the fly using the scraps leftover from Zack Snyder's movies.
All things considered, the current state of DC Films seems to finally be getting back on the right track, giving more freedom to its directors and developing a slate of diverse movies. Unfortunately, it cost almost everything to get here, and it didn't have to.