It has been suggested by a CDPR developer that The Witcher 4 will continue Geralt of Rivia's saga, but in what capacity, we just don't know.
The Witcher Saga - The Lady of the Lake - Part I
CDPR's Sebastian has said that Witcher 4 will continue Geralt's journey in some way. : r/witcher
Lost Ark x The Witcher: when is the event with Geralt and Ciri coming to the West?
Andrzej Sapkowski - News - IMDb
The Witcher 4: Last Hunt trailer is a thing of beauty
The Witcher series is 10 years old, and Geralt is still a badass
Reports claim The Witcher will end at season 5
Liam Hemsworth Is Geralt Now, And Everything Else We Know About The Witcher Season 4
How would you feel about more survival mechanics in The Witcher 4? Similar to RDR2? : r/witcher
Over 250 developers are already working on The Witcher 4, confirms CD Projekt