CD Projekt Red still isn't planning to make a fourth game in the blockbuster Witcher series, but that doesn't mean the developer won't be making more games set in the same universe. Because, let's be real, Geralt's story was never the most interesting one in The Witcher series. Most of the supporting cast are far more nuanced than our grizzled protagonist – especially in CD Projekt Red's adaptation – so these side stories will likely prove incredibly interesting. I'm going to hazard a guess that they'll be something like the Death of the Outsider but for The Witcher series.
Speaking to Strefa Inwestorow (and translated by IGN Poland), CD Projekt CEO Adam Kiciński explained that while the company sees Geralt's Witcher trilogy as definitively finished, the company still owns the IP. Kiciński went on to say that the company will "probably" return to the world of The Witcher, as both fans and investors would be disappointed if they didn't. And really, they'd have to be both stupid and blind to not want to make more money off that IP.
For now, we have no definite games announced nor even the rumor of games coming out, but, we can assume this means we'll be getting some new games games set around different characters, or in different time periods in the story, or perhaps completely different stories altogether. Like, say, a game set during a time when Witchers were much more common than they are in Geralts day. A few hundred years earlier, perhaps. Or maybe set during some of the world-shaking battles that are mostly just glossed over out of Geralt's need to be politically neutral (which he ultimately fails at, but you know how that goes).