Gerwig's leverage and her silence
Complicating things further is Gerwig herself. As she was hired to both write and direct the original film, she reportedly refused to include sequel language in her contract, meaning Warner Bros. proceeded on the first "Barbie" without any guarantee of a follow-up. That decision, which looked like a gamble in 2022, now looks like a smart move, it left Gerwig with all the leverage once the film became a hit.
Gerwig and her writing partner (and husband) Noah Baumbach reportedly do have a story in mind for a sequel, but they're not sharing it with the studio until contracts are finalized. It's a modern Hollywood standoff: no script until there's a deal, and no deal until everyone agrees on the price.