The DCEU was thrown for a real loop last week when it was reported that Henry Cavill was out as Superman and that Warner Bros. was looking at ways to replace the actor. If the news is real, it's just one more challenge for the typically down-on-its-luck superhero universe. Warner Bros. usually has no less than 100 movies based on DC Comics characters in development at any given point (we're not great with math, but you get it), and one of those projects is Supergirl, which is supposedly seen as a potential substitute for Superman. There's already a successful version of Supergirl that exists as a TV show over on The CW, so the movie version would have to be different in a few ways.
The Supergirl project (which is not being directed by Reed Morano) is already off to a solid start. The movie is supposedly a period piece set in the 1970s, distancing itself from any kind of continuity with the present day DCEU. It's also being reported that the main villain of the movie will be Brainiac, which makes sense given the characters ties to Krypton's destruction. While nothing about the Supergirl movie is confirmed, setting it in the past is a great way to separate it from the TV series. That show may take place in another dimension from the rest of the Arrowverse, but it's still firmly in the present. By making it take place in the seventies, it's already got a different feel to it.
One of the biggest ways that the movie can split from the show is by having Supergirl stand apart from Superman. The TV show's Kara Danvers is her own person who has stepped out of the shadow of her famous cousin, but Superman is still a heavy presence on the show, at least in spirit. For example, Supergirl was given her own Lex Luthor in the form of Maxwell Lord. Very much a Luthor wannabe, the series ditched him for an actual Luthor, Lex's sister Lena. The twist is that Lena is a very close ally of Supergirl, flipping the typical formula, but it still felt the need to have a Luthor because "Super" was in the title.
The villains don't stop at the Luthor's either. Superman's rogue's gallery is handed to Kara, who fights baddies like Parasite, Metallo, Cyborg Superman, Livewire, Toyman, and Mr. Myxlplyx. In the comics, Supergirl really doesn't have many good villains, so I can hardly blame the show for borrowing the Man of Steel's, but the DC universe is a big place, and the movie can find plenty of non-Superman villains for Supergirl to fight. As stated before, the movie might include Brainiac, one of Superman's greatest enemies, but that makes sense because he has a history with Kara. Still, Brainiac is a big enough bad that the studio might want to save him for later.
The Superman-ness doesn't stop with just the villains. Supergirl's personal life is eerily similar to Clark Kent's. Part of this is by design, the age-old, 'if it ain't broke, don't fix it.' Kara Danvers is a mild-mannered woman in glasses who no one expects could ever be the great Supergirl. On the show, she even works at a media company as a journalist, the same profession as Clark Kent. If the movie dives into her personal life, then it should avoid giving her the same job as Superman. The characters already have enough in common as it is.
Being different enough from the show is essential, but that's not to say that the show doesn't have merit. It's actually quite solid and has a great central character. Supergirl is a source of hope and optimism when things look bleak and is a positive influence on those around her. The show also isn't afraid to dive into social issues, such as using aliens as not-so-subtle metaphors for immigrants. Plus, it can get very comic book-y like having an ex-boyfriend getting sent to the future, and then coming back with a wife. These are all aspects that would be great for a movie to emulate, but it can't just copy and paste them.
There's a possibility that the Supergirl movie doesn't even happen but with Wonder Woman as the DCEU's most successful movie and a potential future without Superman, Supergirl is a logical and excellent choice to add to the shared universe. There's nothing wrong with adding another female hero to the mix and Supergirl on the CW has laid out a lot of groundwork already for getting audiences to like the character. We can only hope that a movie takes what everyone loves about the show, but makes it fresh enough that it offers a new experience in the movie theater. Otherwise, what's the point?