are reporting that The Witcher 3 will have dlc, but more importantly if you're playing on PC, that dlc will be free.
CD Projekt are very much a PC developer, Witcher 2 notably had a huge update patch for free on the PC to coincide with the 360 release, they have no DRM (which has led to a bit of a spotlight on them regarding the Witcher 3 Xbox One release), and they regularly have sales.
Unfortunately, as have become apparent with the Xbox One drm issue, CD Projekt don't get that kind of control when it comes to the console releases of their games.
“It’s too early to talk specifics, but definitely all the DLCs and updates will be free,” he said. “Of course, we’ll see what the platform holders will allow – what we can do for free [on next-gen consoles]. I mean, there are different business models on consoles. From our standpoint, we’ll definitely do everything we can to deliver the same experience across all platforms.”
So don't hold your breath from free console dlc but there is a chance, or at least a chance that some of it will be free