That’s already happening: Stardock have released a Builder’s Kit DLC that includes new ship parts, a new ship type, and a labelling system so you can name all your fancy designs.
Galactic Civilization III [official site] felt to Adam in his review like a good starting point that years of DLC and expansions would ultimately make more interesting.
There’s also a new labelling system, letting you use letters or numbers to display on the side of your vessels.
The Builder’s Kit is available now through Steam or directly from Stardock and costs $5/€4.