I think it seems to be going in a good direction where both Kerbal 1 and Kerbal 2 maintain good nitches.
Kerbal 1 seems to be very much a "near future/basically the present" tech and space simulator: limited scale, more or less current tech, similar missions (sampling, satellites, exploration, space stations).
Kerbal II being a "mid future" space game would make a lot of sense: more large scale colonies rather than scientific outposts, much more "speculative, but still well grounded" tech. A lot of the advancements to the game to make that nitch filled properly would actually be economic and management I think.
For example, you could build a "lunar shuttle" which you could design and save as a "general template". Then, you could launch that from a designated space port, then have it dock with a space station. And then save that as a "rout".
There after, you can build that craft and asign it to that rout and bam, automated supply lines: the ship can be steadily autolaunched from that space port to that space station once there's some set amount of weight ordered to fill a launch.
Basically, I think the reasonable step is to take you from being space explorers to space truckers, with the relatively complicated (but not too complicated: its still primarily a space sim, not a corporate sim) uptake in the economy.