Even by Arcen standards, things seem slow (but I'm sure they are not). An expansion will come...eventually, although I will be the first to admit the best time to make it has past.
If ANOTHER expansion was released too soon, when the first expansion hasnt been out all that long, it'd only cause trouble; people so easily get the perception that a game/expansion/DLC is being "rushed" when there's not enough time between them, and that usually has nothing but negative effects.
It's been awhile since I've had a full go at it myself, but then I got kinda burned out from designing, working on and endlessly testing the attack patterns and balance for the Obscura and new smaller ships over and over and over and over and over. I never really found that the actual gameplay (either for the solar map or the combat) ever got uninteresting, but I do think it needs more options. That's one of the things that keeps AI War so fresh, is there's about a bazillion different things you can change, making each game very different from the last, even if you only have the base game installed and none of the expansions.