Micromanagement would be an interesting addition.
To a game producer, my suggestion would likely be insane. I do not believe any company that produced a game like I'm about to describe would be able to reap a profit from it. This is purely hypothetical.
Set in the beginning of the war with the Kilrathi, Wing Commander 6 would feature an star cast of talented actor/actresses in DVD-quality FMV. The singleplayer focus would be on telling a quality story and on gameplay. The game engine would need to be feature-rich, allowing for multiple gameplay modes (piloting a fighter craft is not enough anymore, I believe). I would say designing for operation of capship turrets (if not capships themselves), troopships, and for ground combat as well as the usual would suffice; the ability to switch between these modes quickly and fluidly would help, especially in the multiplayer department (I think if a new Wing Commander game were released without multiplayer, many fans would be disappointed, but would still buy it). A command stucture would be interesting, as the Colonel suggested. Fully establishing these modes as character classes with experience modifiers would pull in RPG fans. The graphics engine should allow for a large number of entities (fleets, debris, etc) and be able to render them efficiently. This would allow for the possibility of full fleet actions.
Imagine commanding an Exeter or a Manassas against Fralthis and Ralaris... or perhaps manning the guns or torpedo tubes on such a ship, or anti-spacecraft turrets. Of course, the traditional role of fighter or bomber would still be needed, but the added roles would prove both an exciting avenue and a terrible challenge to developers. How do we design a story around this gameplay? Do we have individual stories for Marines, pilots, etc? Or do we have a basic story for all characters? That's the one detail that really concerns me.
One final idea: What if Confed forces weren't the only playable forces? A full and dedicated implementation of playable Kilrathi forces would add immensely to the game. I personally would enjoy playing as a Kilrathi pilot, commander, etc. It would require a different mindset (pack mentality, perhaps?), but that variety and challenge would be welcome. Anyway, I've gone on too far. Tell me what you think.