It's a bit of a ways down the road yet, but what I'm thinking of a game where the players take the roles of powerful individuals and/or organizations that are vying for power and influence within an interstellar state (or states). Ideally, it'd be pretty simple and intuitive rules-wise, but would still have enough heft to be able to handle and differentiate between, say, outright military actions and more subtle diplomatic or economic maneuvers.
Mind you, this is all still simmering in the back of my mind, so there's nothing definitive yet. In the best of all possible worlds, the game would seamlessly integrate with the RPG so that you could play out the effects of one on the other. I'd love to be able to see players take the roles of, say, the emperor, noble houses, megacorporations, and so forth and then watch as their machinations affect the adventures their characters have in the RPG. Another possibility would be to use rules of this sort to help create an Imperial SF setting, effectively making the game a way to develop the history of the setting, etc.
Maybe it's a pipe dream but I plan to try nonetheless.
I'd love it to turn out to be as nifty as Pocket Empires, which, as you say, various issues aside, was a mighty fine book of its type. I also recall "the Game" that GDW ran internally to plot out the history of its 2300 AD game. I remember being very disappointed to discover that, despite its name, it didn't have any hard and fast rules and was an ad hoc kit bash among veteran wargamers. Still, I love the idea of a political-economic-military-social simulation of history as a tool for roleplaying. I'm pretty sure it can be done; it's just a question of creating the right balance between ease of use and the complexity of the subject matter.
I'm working on The Pilot's Guide to the Core Worlds this month, but, after I finish that up, I'll probably give some thought to "The Game of Empire" (or whatever I wind up calling it).
As far as I'm concerned, that's the single most exciting project I've heard about in RPGs since... well... Thousand Suns. :) What can I say? I really dig the game. It's my true love Traveller all over again, except without the impossibly huge setting strangling the life out of it.
I can only hope that I can help make this book see the light of day somehow...