The Marvel Cinematic Universe might miss out on Cassie Lang's perfect origin story since Kang the Conqueror being the villain, but the other was revealing Cassie Lang was recast, as Kathryn Newton took over the role.
Marvel's decision to recast Cassie Lang with Kathryn Newton has been seen as confirmation that she'll become a superhero in Ant-Man 3. The MCU planted the seeds for Cassie's superhero transformation in Avengers: Endgame could include her origin due to Emma Fuhrmann playing an older version of Abby Ryder Fortson's Cassie.
The recast Cassie Lang for Ant-Man 3 makes it very unlikely Marvel Studios will utilize this origin story.
The key reason that Ant-Man 3 will most likely avoid this Cassie Lang origin story is the recasting decision. The MCU has recast various characters in the past, but the franchise has so far only moved those characters' stories forward and not backward. This helps preserve the limited illusion of the MCU canon and not mix up when the different actors played the characters. With Kathryn Newton playing Cassie in Ant-Man 3, Marvel will surely avoid also having her play Cassie during The Blip. If they did that, the timeline order of actresses to play her would be Fortson, Newton, Fuhrmann, and then Newton again.
While it is understandable to a degree why Marvel Studios wanted Newton, who is a bigger name and more recognizable face, to play Cassie in Ant-Man 3, it is unfortunate that it likely robs the character of this origin. It would've been a refreshing way to tell the origin of a legacy-style character. Cassie's origin and training alongside Ant-Man and Wasp could now feel quite similar to Kate Bishop and Yelena Belova's recent stories. Hopefully, Ant-Man and the Wasp: Quantumania has a clever and unique Cassie Lang origin story in store despite the recast that sets her up for the Young Avengers.
