The runtime revealed on the side of a batch of film cans is the actual runtime of Zack Snyder's director's cut of Justice League, Snyder confirmed on Twitter today. The filmmaker, who reportedly departed the project shortly after the first assembly cut was presented to Warner Bros. executives, weighed in on Twitter to correct a reporter's misconception that something more than three and a half hours was probably the assembly cut. In fact, according to Snyder, the assembly cut was almost five hours long, meaning that the 214 minutes of the version pictured was an hour-and-change reduction. Whether those changes were made before he left, or in the time since Joss Whedon stepped in to finish Justice League, is not entirely clear.
Snyder's "director's cut," were it ever to be revealed, would be probably the biggest change from one cut to another of basically any major motion picture ever released. For context, it seems like about 90% of the content in Snyder's movie never found its way to theaters, whereas even when Richard Donner did his cut of Superman II for the home video market 20 years after its original theatrical release, the difference was not huge -- in part because Donner was fired from the movie early enough in the production that he did not have all of his shots yet. Snyder, it seems, had a pretty complete movie (plus or minus a few scenes that don't seem intrinsic to the main plot).
Justice League Part One and Part Two were announced at the same time, with filmmaker Zack Snyder supposedly filming them back to back. That did not last long, though. Snyder eventually, famously, either left Justice League or was forced out shortly after the death of his daughter. But even before that, a set visit during production on the film included quotes that indicated that Part Two was not guaranteed to happen, and might not happen with Snyder even if it did. Conventional wisdom says that before he exited the movie, the plan was to build a trilogy of films, but even at its most bullish, Warner Bros. only announced the two before things started to change.
When Justice League was released in 2017, with Snyder as the sole credited director of the movie but everyone knowing that Joss Whedon had overseen significant reshoots and dramatically cut the film back from its original runtime to meet studio demands, the film was relatively well received -- as long as the bar you are using for that statement is the one set by other DC movies, which up to that point had been largely hated by critics and divisive among fans.
Its poor box office performance cemented what many fans already expected: Snyder was done with DC films for the foreseeable future, and Justice League Part Two was shelved indefinitely. It seems that the best, if not only, chance to see new, Snyder-directed DC content for the foreseeable future would be if Warners releases a the Snyder cut of Justice League -- regardless of how long a shot that might be.