According to the careers page on Creative Assembly's website, the studio is hiring new staff for what, according to an insider report, aims to be "the biggest multiformat project Creative Assembly has ever undertaken".
Specifically, we're talking about the division of the studio that has, in the past, worked on the likes of Alien: Isolation and Halo Wars 2. As you can read via the job descriptions, the outfit is looking for a Senior Meta Game Designer, a Lead System Designer and a Lead Technical Artist.
As for the first job position, the Senior Meta Game Designer will have to deal with the realisation of "economy, progression and retention methods, leaderboards, challenges, world building and events", so it is entirely possible that this new project will be designed with a strong multiplayer aspect in mind; could it be something similar to, say, Destiny or The Division?
As for the other two positions, we only know that they will have to deal with the development of weapons, gadgets, abilities, and physical-based rendering, so we don't have very specific details at moment, certainly nothing that might suggest anything about the exact nature of the game.
We hope that Creative Assembly will update us on the development of this mysterious unannounced game in the not so distant future. What do you expect from CA's next project?