As for me, there is no point in waiting for the fourth part of The Witcher. The story of the White Wolf is over, in addition to this, there are many endings in the third part and details of these endings too. It is unlikely that the developers will be able to take this into account in the fourth part, and if they do not, then the choice of players from the third part will simply be worthless. What is most likely is that they may release a prequel with a different main character.