I would want them added are additional factions.
Diversity of play is a key element in these types of games - its nice to not always face the same opposing forces.
* Republic - clone wars
* CIS - clone wars
* OLD republic - kotor era
* Sith empire - kotor era
* Corporate sector
Of course, as others have stated it would be cool to see a few cross overs - after all, some ships do cross the somewhat blurry lines here and there.
Finally, to the person who says "but a battle were Imperials are fighting old republic is not realistic" - neither is the same faction fighting with both sides fielding vader .....
Anyway, just my two cents. Oh, and I would love a good large scale battle ground game too!