CDPR recently announced that Gwent will soon be getting its very first major expansion. More importantly, however, they also revealed that the Thronebreaker expansion won't just be a simple influx of new cards, but rather a lengthy singleplayer campaign with a focus on storytelling! The details are still fairly vague, but if CDPR says we'll be getting some "thought-provoking" quests to embark on, I am inclined to believe them given the quality of The Witcher 3's expansions.
Similarly, not much is known about the story itself, but if you're interested in a brief teaser you can find the recently posted announcement video right below. I'll also include a short overview that came with the announcement, though I'm afraid you won't be finding out much in terms of details just yet. Anyway, have a look:
"Thronebreaker spins a truly regal tale of Meve — a war-veteran queen of two Northern Realms. Facing an imminent foreign invasion, Meve is forced to once again enter the warpath, and sets out on a dark journey of destruction and revenge. Cast with rich, multi-dimensional characters and choice-driven, your decisions will shape the lives of Meve and her kingdom."
Thronebreaker will feature a variety of new cards specifically designed with the story campaign in mind, so expect to see some completely ridiculous effects that would never be balanced in a multiplayer match. Besides new cards, the campaign will also have you manage resources, recruit and develop units, and even build your very own (and highly customizable) army in order to achieve total victory. Its certainly an interesting concept, so here's to hoping Thronebreaker manages to live up to expectations!
The release date has not been revealed just yet, but what I can tell you is that it will be coming later this year. As far as new cards are concerned, there will be 20 of them in total, all of which you will unlock by finishing the campaign. I'm assuming you'll also be able to craft them with in-game currency, though nothing has been confirmed just yet. Once more information arrives I'll make sure to update you, but until then I'm afraid we're simply stuck waiting.