No other faction has any meaning at the scale of The Empire and the mess that is how The Republic/Rebels/New Republic/Whatever is portrayed as. That is why games like Empire at War more or less made a super crime syndicate that controls most of the other crime syndicates.

The Hutts are full of infighting and bickery. But even if they WERE united… they would still not be a significant threat in any Total War style campaign. I could see something treating the crime syndicates and smaller factions as akin to Rome (different families/sub-factions that are expected to take over the rest eventually) but that still doesn’t work when The Empire is the size of the entire super-faction as of Turn 1.

Star Wars as Terra Invicta would be fucking amazing and a really good fit because espionage, guerrila warfare, and insurrections are a thing. I could even see a case for Star Wars as Crusader Kings. But Star Wars as a Total War or a Europa Universalis just doesn’t work.