"The PC version of The Witcher 3 will have absolutely no DRM from day 0. Zero. Zip. Nada. It doesn’t matter if you choose to buy it on GOG.com and support us directly or buy the game in box format, you’ll still get the 100% DRM-free experience. And this goes for the whole world."
The Witcher developer has dabbled in DRM before. It was unceremoniously patched out of The Witcher 2. Momot commented on this in the post. "We’ve fiddled with DRM in the past (Oh boy! How young and naïve we were;)) and that’s enough. Lesson learned."
Of course, if you buy the game through Steam you'll be dealing with Steam restrictions, "but where CDPR does have control — like GOG.com — there will be absolutely no DRM."