According to the BBC, Jodie Whittaker's Doctor Who replacement will be revealed in "the coming weeks." That's sooner than we expected, though it does make sense when pre-production on the next iteration of this iconic sci-fi character will begin gearing up as the current series nears its end. It's also likely that we'll see the 14th Doctor make their presence felt during Whittaker's sendoff.
It's also been confirmed that two former Doctor Who companions, Tegan and Ace, will return for Whittaker's final episodes as the 13th Doctor. As you may recall, Janet Fielding played Tegan Jovanka from 1981 to 1984 alongside Tom Baker and Peter Davison's fourth and fifth Doctors.
Sophie Aldred joined the Doctor Who cast as Ace in 1987 and was part of the series until 1989.
Whittaker was cast as the first female Doctor in 2018, and while Hugh Grant has been rumoured as her replacement, we've heard nothing concrete about who is going to take over the role from her.
However, what we do know is that current showrunner Chris Chibnall is also exiting the series in 2022 after a trio of specials this year that have been described as an "epic blockbuster event." The first of those, "Legend of the Sea Devils," arrived on April 17, but the next two don't have release dates.
From there, Russel T. Davies, who revived Doctor Who way back in 2005, is returning to the series to celebrate the iconic time-traveler's 60th anniversary. You just know he has big plans for the Doctor, but it doesn't appear as if we should expect to see Grant joining this franchise to play him.