After some confusion on whether season 3 of The Mandalorian would premiere in December 2021, Jon Faveau confirmed during his appearance on GMA yesterday that spinoff show The Book of Boba Fett (which is now in production) will air on Disney Plus December 2021 while production on The Mandalorian will begin after that, due to EP Dave Filoni writing the Ahsoka show starring Rosario Dawson.
While The Mandalorian's third season has no official premiere date, it's definitely going to be in 2022. Fans will have to wait over a year to see what happens after the dramatic ending to the second season.