So, just spitballing here, but this game seems very much focused on the rebel/imperial battles. I suppose the game is small enough scale that you could have a 'scum and villainy' faction, but I don't think it would make much sense in the grand scale of things. When would they organise themselves fully toward a battleground kind of scenario.
That said, there are lots of characters from that side of the universe that people love and wouldn't be out of place in a game like this, so I'm suggesting that there may be a fringe colour of units that can be recruited to either side? A sort of grey area, where you can hire them regardless of which faction you're playing. This could include bounty hunters and units that were unsavoury types, but potentially the kind that both the rebels or the Imperials may end up hiring to bolster their own ranks.
We know that even many imperial generals looked down on the use of bounty hunters, but Vader used them anyway. I'm sure the same applied to commanders on the Rebel side.
Is there flavour/EU potential here? Or am I stabbing in the dark.