I bet it will be a "not many races-many faction/races" feature. Less, less, less ship-designing..
Think of StarCraft

Terrans:
Confederation
Sons of Khoral
Umojan Federation (?)
Kel-Morian Protectorate (Something like that..)
so about the Zergs, and etc..
If you applied it to GalCiv2, you would have the Terrans, the Torians and the Drengins. But there would be:
-Drengins who still are in their homeworld
-Drengins who lives near the former Torian enslaved world, and allied themselves with them against their former homeworld
-Korath who plans to destroy the galaxy
-Torians who lives on their homeworld
-Torian refugees who seek revenge at all cost
-(Insert other Torian faction idea)
so about the Terrans.. Would be neat. Specially if, when you play the Terrans, you really had to deal with internal political arguments betweens internal factions