We know that the next expansion pack for The Witcher 3 will be the Blood & Wine DLC and that the DLC will be released this year but so far, CD Projekt Red have not really revealed much about what the DLC will be coming in with.
However, they might have accidentally leaked some details about the DLC on their own Forum. The info was seen in their Forum but was soon taken down but we all know that once it is up there, it is all over.
Some fans managed to capture the details before it was taken down and posted it on Reddit. Based on what they have seen, it looks like the next DLC will have some to do with the Brotherhood of the Wolf although they did not elaborate on it.
It was also pointed out that the DLC will be coming with a new sword called the Bone Sword. There will be new Gwent card to collect as well as a few new combat moves. The post also states that the DLC will come with three ending, 2 standard and one secret engine.