Game Pass just keeps getting better and better.
The Witcher 3 Game Pass

CD Projekt RED and Microsoft announced today at X019 that The Witcher 3: Wild Hunt will soon be available through the Xbox Game Pass program. This means that Xbox Game Pass for Console and Ultimate will be able to download and play one of the best RPGs ever made at no additional cost.

This release includes the content found in the base game, Wild Hunt, plus 16 free pieces of DLC. It wasn't specified anywhere that this release also includes the game's two expansions of Blood and Wine and Hearts of Stone.

I suppose we'll find out for sure on December 19 when The Witcher 3: Wild Hunt is added to the Xbox Game Pass. The Witcher 3 is already available for direct purchase for PC, PlayStation 4, Xbox One, and even the Nintendo Switch.