But there is no demand for a JLA movie outside of fanboys. Why is this so hard to understand? Nobody cared about the Avengers. Even Hulk played as more of a caricature than bankable blockbuster material.
There is no demand to see WW, GL, and Flash team up in a film. The GA does not care about these characters. Batman and Superman would be like Spiderman and Hulk teamed with guys like Dr. Strange, Ant-Man, Hawkeye, etc. There is a jarring disparity.
There was a disparity more or less with the Hulk and the rest of the Avengers, but they built them all up and made the public care. Four years later, you have a franchise that is a lock for 3.5-4 billion dollars over three films, barring a royal **** up between now and then.
The difference being I don't think DC needs something like the SHIELD or extended Flash roles in a Superman movie like Marvel has been doing. That undermines the solo movies. I think they can just come together and it will work because it has already been done before. The DC universe does not ground itself in reality to the extent Marvel does.