I think at this point, the plan is to transition AI War and all 6 expansions into a sequel, with added features and content, plus mod support (yayy), on an upgraded version of the Unity Engine.
See
this thread for more details.
There's no TBA for that at this point, and it's not for certain, but I would assume that if it was the project after Stars Beyond Reach (which it may or may not be), it would come out near the end of this year or early next year. That's just my personal estimate, I in no way represent Arcen.