It'll be a real shame if they never make another Witcher game. Yes I know it's based on the books but they could happily invent a new story along the same lines.
They won't. Their next project is Cyberpunk 2077 and they'll be moving on to something different from there. There's zero chance of another Witcher game being made by CD Projekt but I don't doubt that other studios will try to acquire the rights to the series.