Next year's Arrowverse crossover event is already confirmed to be an adaptation of DC Comics' Crisis on Infinite Earths, but considering how different The CW's DC TV universe is compared to the core DC Universe, certain things should remain different on television, such as the 2019 Crisis potentially killing off Superman instead of Supergirl. In 1985, DC Comics launched the Crisis on Infinite Earths crossover, which became one of the biggest and most ambitious comic book events of all time.
Since the DC Universe at the time consisted of multiple parallel universes and several different versions of iconic characters, with some even have conflicting storylines, it became clear that DC Comics needed to do something in order to merge all the timelines and universes together. It forever changed the DC Universe - and that meant killing off notable characters in the interim, such as The Flash and Supergirl. But what if, instead of killing off characters that people are expecting, the Arrowverse's Crisis on Infinite Earths kills an iconic character they've been ignoring?
Superman (Tyler Hoechlin) first appeared in full in Supergirl's season 2 premiere episode, "The Adventures of Supergirl," and he's since been a recurring guest star, helping out his cousin in a handful of events. However, Superman isn't the star of the show or of the universe, despite being the oldest superhero there is. He's been largely ignored in the grand scheme of things, and since his story wrapped up nicely in Elseworlds, he's now a prime candidate to be killed off in Crisis on Infinite Earths. It would be astonishing to see George Pérez's memorable cover art for Crisis on Infinite Earths #7 recreated with Supergirl holding Superman instead, after the Supergirl TV show already teased Crisis with Superman holding Supergirl.
To add to this, Superman's story in the Arrowverse isn't one that's going to continue to expand. Earth-38 is Supergirl's world, and Superman only comes in during major episodes, such as season premieres and finales, and then potentially in the annual crossovers. But now that Superman has seen Supergirl's "destiny" and that he's ready to hang up his cape, it's possible that he may make the ultimate sacrifice in the Arrowverse's Crisis on Infinite Earths. It would fit into the overarching narrative and truly allow Supergirl to shine on her own, without having to worry about Superman.
A crossover of this magnitude must have consequences, but since the eponymous characters of two of the Arrowverse's shows die in the comics, the network ideally wouldn't allow the producers to kill off those characters on television. They can't just end two of their shows, especially considering how successful they are. Instead, killing off Superman - and potentially Oliver Queen, which would allow Emiko Queen to become the new Green Arrow - would still deliver an impact to audiences but keep the status quo. It's both safe and bold at the same time.