Polish website Game Exe received a comment from Marketing Manager Karol „PanKarol” Zajączkowski on the recent departure of Artur Ganszyniec, as uncovered by GameBanshee. A translation of the statement (courtesy Ausir):
Yes it is true, by the end of February, Artur has left RED.
He did so at his own request, because in addition to The Witcher he has a few writing projects of his own, on which he now decided to focus.
The fact that Artur had gone, does not mean, however, that now there is nobody to deal with the plot - he was part of a team of more than a dozen really great people who, despite this turn of events further work on the story, so it will have the same level of quality. In addition, the plotline has already been outlined - now most of the time is spent on implementing things which Artur and others have already created some time ago, so there's no need to feer that the end of the story will be written by someone else than the beginning.
In short, you have nothing to fear - everything will be good or even very good.