I would reccomend that CS look at what the demand is like (as they said they would) and then guage off that what to put there efforts into.  I've personally used a space simulator called Orbiter and it is quite popular.  I don't know if anyone here knows about it but it is highly realistic in terms of physics.  As for visual quality, there is lots of room for improvement.  CS already NAILED the visuals.  Just show your support for the new space sims and CS will probably look at what you want and see if it is possible.