Looks like Loki TV show head writer Michael Waldron is becoming something of a Marvel fixture. Already on board to write one of the future big Avengers team-up movies, Avengers: Secret Wars, he's now — according to Deadline, at least, cranking out the script for the film that will lead into it, which (for now) is called Avengers: The Kang Dynasty.
Waldron, in addition to crafting the concept for the Loki series and running it alongside Eric Martin and director Kate Herron for Season 1 (other duties kept him away from Season 2), wrote Doctor Strange In The Multiverse Of Madness and new projects under a big deal with Marvel/20th Television via his production company Anomaly Pictures.
So, assuming he stays aboard for both, Waldron will be responsible (on the script front, at least, for closing out Phase 6 of the Marvel Cinematic Universe).
We say, "for now" about Kang Dynasty, because there have been serious rumblings that Marvel will move away from Kang as a new big bad in the light of actor Jonathan Majors' ongoing legal issues. So it's entirely possible that Waldron is writing a non-Kang story but can't say anything yet. And both films have been in flux anyway, since Kang Dynasty recently saw director Destin Daniel Cretton depart.