Cataclysm had the right idea in a way, but went about it wrong. I quite liked the idea of the Kiths still struggling for power, and different ship-types emerging for different Kith, that could have put a whole new edge on Multiplayer and you played, for example, Kith S'Jet vs Kith Manaan or the like. S'jet would be high Tech, Manaan would be warriors.
However, the game didn't quite pull it off right. Homeworld 2 and the kind of Mega-Zen storyline looked great but was a wee bit esoterical

But then, I seem to recall the original promise of homeworld 2 was 8 different multiplayer races :/