Not much is known about James Gunn's script for his Guardians of the Galaxy threequel or its production. Current information about the production indicates that that plans for Guardians of the Galaxy Vol. 3 went unchanged due to the ongoing pandemic, that “most” of the production heads have been hired, and that shooting will begin in late-2021.
As for the script, all that's been reported is that James Gunn went into writing the script knowing that Gamora would die in Avengers: Infinity War, that Chris Pratt's Peter Quill will still have a big role, and that someone will die in his sequel. The script has also kept the same working-tile of “Hot Christmas,” and that Dave Bautista described “...a lot more interaction with [Drax] and Mantis,” at least the last version of the script he read.
Dave Bautista was recently interviewed by Entertainment Weekly, in which he gave more information about the progression of Guardians of the Galaxy Vol. 3 and its production, confirming that “...we will go into production late next year.”
Bautista also spoke about the script and the possibility that it has changed since the last draft he read, saying that:
“I saw a script early on when we were all on schedule and James Gunn was attached before everything went nutso. I believe because [Marvel's] whole calendar has changed [due to the pandemic shutdown], that storylines have changed, and they won't intersect like originally planned. Obviously, we lost Chadwick [Boseman], so I don't know where that leaves Black Panther."
However, Bautista clarified that “I haven't seen a new script, is the short answer,” meaning that he and likely the rest of the cast haven't been given access to Gunn's latest draft yet.
WHAT THIS MEANS
Again, as Dave Bautista stated, he hasn't had access to a new script yet, at least a different version from the last one he was given. Still, it's unlikely that there have been any significant changes to the script, as James Gunn was directly asked about this possibility on Twitter and replied that “very little” was changed.
It isn't a surprise that not a significant amount has been changed, since when James Gunn was “fired” by Disney, he had already completed it, and production was meant to begin in several months. Additionally, due to the franchise being naturally separated from the rest of the MCU, any schedule changes wouldn't really risk affecting it, especially since the events of previous movies, in-universe, were only separated by three months.
The only likely change to have occurred due to the schedule change and delay in production would be Thor's place in the movie, as Gunn has confirmed that Thor: Love and Thunder would take place before Guardians of the Galaxy Vol. 3. Considering the space-faring team will already have a significant presence in Thor's fourth outing, it is unlikely that the God of Thunder will be in the James Gunn's threequel.