Sequels are practically a given for any movie that does well at the box office and it when it comes to superhero blockbusters starring popular characters, sequels absolutely are a given. However, it seems that the upcoming Wonder Woman 1984 isn't really a sequel. At least, not according to the team that's making it. Producer Charles Roven says that director Patty Jenkins isn't approaching the movie as a sequel. It seems she draws a line between the idea of telling another story and telling a sequel story. According to Roven...
[Patty Jenkins] was just determined that this movie should be the next iteration of Wonder Woman but not a sequel. And she’s definitely delivering on that. It’s a completely different time frame and you’ll get a sense of what Diana-slash–Wonder Woman had been doing in the intervening years. But it’s a completely different story that we’re telling. Even though it’ll have a lot of the same emotional things, a lot of humor, a lot of brave action. Tugs at the heart strings as well.
Technically speaking, a sequel is a story that's designed to continue the story that was started in an earlier work. Wonder Woman 1984 will continue to tell the story of Wonder Woman in as much as the movie will deal with the same main character, but it seems the idea here is that this movie won't really be connected to the first in any meaningful way.
Since the new Wonder Woman movie will take place decades after the first, and still a few decades before the events of Batman v Superman: Dawn of Justice, the movie is set in a good place to tell a stand alone story. We can expect some similarities between the two films, but it sounds like the plan is to make something a bit different in every way.
Of course, we know there will be some connections to the first Wonder Woman film. If nothing else, we know that Chris Pine will be in the movie as Steve Trevor. While we don't know the how or why of that, his appearance is certainly an intentional call back to the first film.
It's not all that surprising to see that Wonder Woman 1984 is being looked at as its own movie. DC has clearly found more success in making standalone movies rather than trying to tie everything together into a single universe. It seems that even goes for two films starring the same character.
Charles Roven's comments to Vulture, at least theoretically mean that even the few people that missed Wonder Woman will probably be able to drop right into Wonder Woman 1984 without missing a beat. If it's not really a sequel then watching the first movie shouldn't be required to enjoy the story of the new film.
We can judge that for ourselves when Wonder Woman 1984 hits theaters in the summer of 2020.