The business honchos at FXS will probably look at how BE1 went (sales were a bit disappointing) and observe that stellaris exists in the "4x scifi" category, and say, "hard pass." You have the engine and framework, but you need the full cycle of making new assets, defining the new gameplay, and especially marketing. What they learned with BE is people expect a full fledged civ game from them; can't turn out anything less than a AAA title.
It's too bad because i think a space version of civ6 would be far superior to a space version of civ5, just given all the crazy new system capabilities we have now. (Weather, loyalty, civil infrastructure, changing terrain, the extremely flexible adjacency system, policies, civics tree, etc.) A lot of the abstractions would make more sense on an alien planet too.
Someone could likely mod this as a total conversion, if we only had the DLL. Alas, they are holding onto that pretty tight.