In a press release announcing the release of The Witcher 3's first expansion, Hearts of Stone, the developer CD Projekt Red mentioned a shift in the release of the game's second expansion.
Originally dated for a Q1 2016 release, Blood and Wine now carries a "first half of 2016" release window, indicating that the expansion may be coming out later than the developers previously planned.
The product pages on both GOG.com and Steam have not yet been updated to reflect the change, but CD Projekt Red says that they will be communicating an exact launch date for the upcoming expansion at some point in the future.
Hearts of Stone adds 10 hours of new content into the game. Even more substantial is Blood and Wine, which plans to offer over 20 new hours of gameplay. The expansion will take Geralt to an all new region of Toussaint with an atmosphere very much unlike the current locations. It's described as "a land untainted by war, where an atmosphere of carefree indulgence and knightly ritual masks an ancient, bloody secret."
We'll update you with new details as they become available.