When DC first began its own cinematic universe, it came to market with a different idea about how to build that universe. Character crossovers happened almost immediately. The second film in the franchise brought together Superman, Batman and Wonder Woman, DC's three biggest hitters. However, it seems that Warner Bros. and DC have decided to change things going forward, and instead focus on individual characters and stories rather than building large crossovers. According to Warner Bros. film executive Kevin Tsujihara...
The upcoming slate, with Shazam, Joker, Wonder Woman 1984 and Birds of Prey, feels like we’re on the right track. We have the right people in the right jobs working on it. The universe isn’t as connected as we thought it was going to be five years ago. You’re seeing much more focus on individual experiences around individual characters. That’s not to say we won’t at some point come back to that notion of a more connected universe. But it feels like that’s the right strategy for us right now.
With Batman v Superman: Dawn of Justice and Justice League being two of DC's early productions, it was clear that the plan was to bring all of DC's major comic heroes out together and make the interconnected universe a major part of the brand.
It was the exact opposite approach that Marvel took when it first began the MCU, making stories for all of the individual Avengers before bringing them together for a major crossover movie. DC may have been trying to simply differentiate itself and not copy the Marvel formula or it may have believed that bringing the Justice League together early was truly the right path, but it seems that now, as Kevin Tsujihara tells the L.A. Times, the plan is to go back to those individual stories.
And what's most interesting is that, for the most part, we're not talking about solo films for the Justice League, but entirely new characters. Wonder Woman is getting a sequel and we expect Batman to get a new movie as well, but Shazam!, Joker and Birds of Prey, the films on the way soonest will all focus on entirely different characters.
Joker as far as we're aware, isn't even part of the existing DC universe as the character portrayed by Joaquin Phoenix isn't the same one played by Jared Leto in Suicide Squad.
This statement makes it sound like, at this point, there are no real plans for another major crossover with DC. Justice League left us with a post credits scene that indicated that the Justice League would have an entire team of villains to take on at some point in the future, though now one has to wonder when we'll actually see that.