The first Wonder Woman movie presented an altered version of the events of World War I, and managed to keep the existence of the superheroine and the Greek gods a secret. Will the same happen in Wonder Woman 2? Based on July’s rumor that Patty Jenkins planned to set the sequel during the Cold War, that appears to be the case.
In July, Screen Rant exposed a scoop (The Wrap confirmed it later) that said the sequel would take place in the 1980s, toward the Soviet Union’s final days. So, no matter what story is told within that setting, Wonder Woman's existence will remain hidden to the rest of the world.
Everything that happened behind the Iron Curtain was surrounded in secrecy, so it’s plausible that Diana Prince could have participated without ever revealing her existence.
According to Screen Rant, the final Justice League trailer presented a possible connection between Justice League (Steppenwolf's arrival) and the presumed Wonder Woman 2 setting.
An important Justice League battle sequence apparently takes place in Chernobyl, which is also referenced in a promotional image featured in Empire. The Justice League trailer also shows that the Parademons fly out of what seems to be a nuclear silo.
All of this confirms that one of Steppenwolf’s bases is located in Chernobyl, possibly because Darkseid might have hidden something underground at the nuclear plant after his first invasion. But what’s the Wonder Woman 2 connection? Taking into account the real-life speculation about the Chernobyl disaster, and the rumored Wonder Woman 2 setting, Patty Jenkins and Geoff Johns could use this place and its history as the basis for the entire movie.
But no one involved with the sequel has confirmed any of this, so take it with a grain of salt.
Wonder Woman 2 will be released on December 13, 2019.