Building Better Worlds is slated for a 2023 release.
Last week, Gaska confirmed in a FB dicussion that what's next up after Building Better Worlds "will likely be a space trucker adventure and spce trucker campaign sourcebook". (My emphasis).
I sort of have a feeling that we'll continue exploring the Border Bombers/Engineers angle going forward, which might very well take us to Origae-6 or somewhere else far beyond the 20 parsecs line. The bigger Engineers plot was sniffed at repeatedly during DoW and CMOM, and -- with Gaska appearing absolutely unafraid to tackle big questions in the game -- I wonder if we won't start untangle that stuff post the marines stuff.
Also, I made a mistake in the past and presumed that Building Better Worlds would get its own cinematic adventure release after BBW comes out, but Gaska corrected me by pointing out that Heart of Darkness _IS_ that BBW cinematic release. (I sort of saw the 3rd installment of the 26 Draconis Strain trilogy as a standalone thing, but it is connected to BBW, which makes me VERY excited for Building Better Worlds!).