Speaking with The New York Times, the writer-director said that the film was set to deal with the Thanos “blip” from Avengers: Infinity War and Endgame prior to Boseman’s passing forced them to change their plans. "'What are we going to do about the Blip?' That was the challenge. It was absolutely nothing like what we made," said Coogler. "It was going to be a father-son story from the perspective of a father, because the first movie had been a father-son story from the perspective of the sons."
As the mid-credits scene in Wakanda Forever revealed, Lupita Nyong'o's Nakia is revealed to have given birth to a child with T'Challa during the five-year blip, which saw the character and many other MCU mainstays absent. The movie would’ve dealt with T’Challa’s absence from his son, and what impact that had on him and Nakia.
"T'Challa was a dad who'd had this forced five-year absence from his son's life," Coogler continued. “The first scene was an animated sequence. You hear Nakia talking to [their son] Toussaint. She says, 'Tell me what you know about your father.' You realize that he doesn't know his dad was the Black Panther. He's never met him, and Nakia is remarried to a Haitian dude. Then, we cut to reality and it's the night that everybody comes back from the Blip. You see T'Challa meet the kid for the first time."
The film also would’ve featured another time jump from the blip. "Then it cuts ahead three years and he's essentially co-parenting. We had some crazy scenes in there for Chad, man," Coogler said. "Our code name for the movie was 'Summer Break,' and the movie was about a summer that the kid spends with his dad. For his eighth birthday, they do a ritual where they go out into the bush and have to live off the land. But something happens and T'Challa has to go save the world with his son on his hip. That was the movie."
Namor still would've been the main villain of the film, but Julia Louis-Dreyfus' C.I.A. agent character Val would've played a bigger part. "It was basically a three-way conflict between Wakanda, the U.S. and Talokan," he added. "But it was all mostly from the child's perspective."
Ultimately the filmmakers pivoted majorly from the original plans, and the film pays tribute to the legacy of Boseman. "[We] wanted to make an ode to [Chadwick] and what he meant to us,” Coogler told Complex last month. “He meant both things to us. Chadwick was very much T’Challa for us, but T’Challa was only a facet of who Chadwick Boseman was and we wanted the film to be an ode to both of those things without sacrificing everything else.”