According to the official Witcher website and a recent interview with The-Witcher.de, the third installment in the series has been confirmed.
The Witcher official website displays a “now hiring” advertisement in bright yellow, a blatant clue of an upcoming development by Projekt RED.
To make things even more interesting, in a recent interview with dev Jan Bartkowicz on The-Witcher.de, the third installment seems to have been confirmed:
(Translated) “That’s a good question Well, I think the problem that some people have is the overall impression. The first part could just as easily be a stand-alone, while the second part of a planned trilogy is now time, logically, have a very open end of the third part has to go. Consider this example for comparison to films like Pirates of the Caribbean, where the first part one self-contained story has, the later is unchangeable, but then you think, it should be a trilogy. So people have a problem then. The end of The Witcher 2 is the beginning of much larger events, while The Witcher one rather a cliffhanger ending was.”