For me, I would be interested in more modern 'what if' scenarios, and anything WW II related. There has been some good discussion here, and I'll chime in with my two cents.
The modern era is under represented, and as Red Storm shows, it makes for a hell of a game. World war 2 may be done to death, but it makes for a very interesting subject tactically, what with all the different, constantly evolving vehicles and equipment, several sides, and fascinating battles. It may have been done to death, but it hasn't been done to death WELL, in my opinion. Combat mission and close combat do a good job with small unit tactics. The command ops series does a good job with operational warfare, but it's a very different beast from flashpoint campaigns. I haven't really liked many of the hex based ww2 games, even the highly rated ones like the Operational Art of War. Steel panthers is fun but too slow for large battles. They tend to be a bit on the dry side for me, and I think, should the developers go the ww2 route, flashpoint campaigns would end up being the defacto standard for operational ww2 games the way Combat Mission has for small unit/tactical ww2 combat. What flashpoint campaigns has in spades is intensity, tempo, and the awesomely frustrating order system, which makes for a nail biting experience.
My other wish would be for current day stuff. Lots of interesting what if scenarios out there to model (which I hope to gods remain what if) with China, Israel, etc. I imagine the latter would be easier to do and would make for excellent expansions.
Ultimately, however, I've been impressed enough with Red Storm to buy whatever comes out next regardless of theater. I know quality when I see it, and FC sits on the shelf next to combat mission, close combat, harpoon, and all the other games that have outlasted their time.