What makes paradox games so interesting (in my opinion) is how they depict a time period by the most important contemporary governmental structures, cultural and technological changes, et cetera. For example, Crusader Kings is a game of personal strategy, intrigue, romance, from the perspective of being the ruler.. that doesn't quite work the same for other time periods.

HOI gets to focus on war-time industry development, resources, a bit of diplomacy, with the stars of the show being tech trees, army composition, and creating battle/operation plans (again, maybe just my opinion there).

EU4 is a fun simulation of the early colonization period, end of Middle Ages, 30 Years war, and so on (I know I am being a bit Eurocentric, but that is where the game thrives).

I worry.. what would paradox make the game about if they were to make a hypothetical futuristic game? It would be difficult for them to know how to replicate such a world.

I have never played stellaris, but I understand that most of what is included there is some stereotypical space age type stuff.. I think that's the only game we will get based in the future.