They probably come back in an expansion. Same for the Torians.
Maybe as some sort of Starcraft's 2 "classic" units, maybe not for Multiplayer (though why not?), but in Single. I wouldn't mind that.
Honestly, to some extent I want more detailed and deeper combat, yet in the same time, I'd rather concentrated on different issues - by my opinion supreme commander (or ruler), whose role we, apparently, playing, shouldn't control each fleet or ship directly, as he shouldn't tell each sailor to go potty and brush teeth after each meal (though it could be funny promotional campaign), he should think big. As any, say, regimental commander should command regiment, not battalion. That's why I liked Endless Space - little involvement into combats. Too bad some involvement, I wouldn't mind to delegate that to appointed commander.
In theory, Galactic Civilizations universe is so big, so we could have several different types of games - military strategy, tactics, deep economy simulation, game similar to X-series, RPG... I understand budget limitations, but can man has a dream?