I'm thinking some form of Trade Station, maybe we'll finally get a Commerce and Trade mechanic.
That said, hope Paradox starts focusing on combat after this unannounced DLC. We've so far had DLCs focused on empire, story, management mechanics, tech tree, balancing etc but very little on combat. I'm sure a lot of players are desperately wanting new weapons & defenses, hell even better, new types of those instead of the usual Energy, Kinetic & Explosive maybe we can have Psionic or Biological catogery. Theres also new platforms like Starbase, new ship class/hull since we're missing a lot of those "in between" like light/heavy cruiser, support, gunship, escort, frigate, battle cruiser, dreadnought, leviathans and so on.