Simon Vale, from Magic Dome books was nice enough to post a translation he did for an answer from Michael Atamanov about whether there will be a 4th Dark Herbalist book.
“I’m starting to write this week as soon as I finish editing the third Reality Benders. I hope to finish it in October. For now I’m not sure if the fourth book is going to be the series final. But taking into account what I’ve already planned for it – probably not. Events in the book will mostly take place in reality, though there will be plenty of in-game stuff too. Perhaps, some of you have already guessed who’s been tombed in book 3 (it wasn’t Timothy)… Anyway, after that there will be a huge squabbling around the richest corporation of the planet.”