The British star would replace Vanessa Kirby in the role following creator Peter Morgan's shake-up that will see older versions of the characters played by new cast members.
Evening Standard reports that the two-time Oscar nominee was in contention to play the role of Queen Elizabeth II before it was announced that Olivia Colman would replace Claire Foy in the role.
Funnily, both actors have previous playing the same royal - the Queen Mum: Olivia Colman in Hyde Park on Hudson and Bonham Carter in The King's Speech.
There is currently no word on who will replace former Doctor Who star Matt Smith as Prince Phillip.
With a third and fourth season yet to receive the official greenlight, early production is reportedly underway.
Speaking about his decision to recast roles, Morgan said: “You can’t ask someone to act middle-aged. Someone has to bring their own fatigue to it. The feelings we all have as 50-year-olds are different than the feelings we all have as 30-year-olds.“
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Bonham Carter will next be seen in the all-female Ocean's 11 reboot, Ocean's 8, alongside Sandra Bullock, Cate Blanchett and Rihanna.
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