In an interview with SF Signal, Glen Cook has confirmed that he is planning to write two more Black Company novels. The first, Port of Shadows, will take place between the first two novels of the original trilogy. He has already done some work on this book (in the form of two short stories which will be expanded into the novel) and will make this his next project once some other existing commitments are met.
There will be another book, A Pitiless Rain, which will be set after all the other books in the series. He does not disclose a timeline for this book. He also confirms there will be another Garrett, P.I. novel in the future, with the working title Wicked Bronze Ambition.
Two of my favorite series so good news indeed. I am always up for a new Garrett PI book. I am not the completist I used to be, and the Black Company trilogies are pretty sufficient unto themselves so I hope the books are worth the read. I am not a fan of jumping back in to the timeline and wedging in material. In a weird way I feel cheated. Adding a book to the end could be interesting because the god-like world-changing levels of warfare pretty much hit the ceiling.
However, you cannot discount the skill of a talented author like Glen Cook get the job done.