Keep in mind this is just me having some fun. I enjoy Theory-Crafting quite a bit. Feel free to leave your thoughts below about these random ideas.
Scum And Villainy
I think this will be the third, and most likely final faction. I don't see them expanding into the Clone Wars despite how much I'd love that. (I'm a huge Clone Wars fan, although I'm not fond of the actual prequel Trilogy) Sucm And Villainy has alot to work with while still remaining iconic, and if they add a 'Unique' keyword that just states, "you may only have 1 of this unit in a list." then I think Scum would be perfect for it. Basically, if they had a Unique keyword they'd be able to make Scum And Villainy have tons of iconic characters. Infact, I'll list some thoughts on possible units below this.

Leader Ideas
Boba Fett: Boba Fett is a pretty obvious "Introduction" Leader. I think if we get Scum and Villainy, he'll definitely be the first leader to appear. I think he'd be able to utilize alot of abilities, and if we got a Unique keyword then I think he'd have some benefit while attacking them. (Since he's a famous Bounty Hunter I personally think it'd be interesting if he got a benefit from attacking Unique characters, however, if the Unique keyword isn't made, which I doubt it will, he could always get a buff when attacking opposing Leaders.)

Jabba The Hutt: I know you guys must think I'm insane, but hear me out here. I think Jabba would be great as a leader for Scum and Villainy because, despite being useless in combat, he could have an ability that makes all his have a higher Morale and perhaps have him be accompanied by two Gamorrean Guards, who would be treated as members of Jabba's squad. But, besides that I'd say he'd be low in HP and would also be beyond bad in combat, however Jabba isn't exactly meant to charge into combat. (Well, I don't recall Jabba trying to tango with Luke in a 1 on 1 duel.)

Bounty Hunter: So I'm sorta hoping that Empire and Rebels each get a vanilla customizable Leader option (Such as Stormtrooper Commander and Rebel Commando) and the Bounty Hunter would be the Scum&Villainy version of that.

Corps
Mercenaries: I'd say 60 points for a squad of 4, with an upgrade to add in 1 more for 15 points would be about right for a group of Mercenaries, which would make them the priciest 'basic' units so far. I think they'd be decent in both ranged and melee, and their models would all be different scum/scoundrels of different races and such.

Tusken Raiders: A ranged unit that'd be terrible close up. Not much else to say here.

Jawas: A 'swarmy' unit. Like, 8 models for 40 points, with a card to allow 2 more for 10 points. (meaning they'd be like 5 points a model.) Yes, they'd be terrible, but also decent since there'd be so many of them.

Special Forces

IG-88s: This would be a Unique Unit. So, they'd work similarly to how they do in X-Wing. It'd be a 2 Man Squad, and you'd have to pick between 2 of the 4 IG-88s. (IG-88A, IG-88B, IG-88C, and IG-88D) Each one would have a different keyword/ability, and they'd share their keywords/abilities with their partner.

Gamorrean Guards: A squad of 3. They'd be big tank dudes that are basically just to soak up damage. They'd have no ranged attack, but they'd be decent in Close Combat.

Supports
Still not entirely sure what counts as a support. I'm assuming small vehicles.
Tusken Bantha Raider : A Tusken Raider riding a Bantha. They'd be kinda slow, and i'm not quite sure how the unit would work besides being good in range and decent close up and having quite a few health points, but I think they'd be a good support.

Heavy Units
Slave I: This would be a Unique Unit. It'd have heavy fire power and would be able to remain stationary in the air. (I say this since we clearly see it remaining stationary in Episode II.)

Skiff: I feel like a Skiff is an obvious Heavy Unit for the Scum faction. Its really Iconic and it'd look great on the board, and I think they'd be quite fast with alot of firing points, and they'd be able to transport up to 1 Squad.

Rancor And Handler: So the Rancor would be pretty frightening, and would have tons of HP and would be devastating at close combat. However, it'd also have 1 huge weakness, in my eyes. I think the Rancor would need ot be accompanied by its Handler, and the Handler would be a bit fragile so you'd have to try to defend it. Anyways, if the Handler were to be killed, that would be when the Rancor's glaring weakness would start to trigger. Basically, it'd have some sort of "Rampage" ability that would take place when its Handler went down, and Rampage would be ' This unit must move toward and attack the nearest unit at all times, regardless of if it is friend or foe.' Basically, it'd constantly just charge at the nearest unit regardless of if its allied or not. (so yes you'd be forced to fight yourself.) The strategy with the Rancor would be to set it up as far from your other forces as possible, and to try to charge it deep into enemy territory so that when(I say when, not if, cause I doubt a handler would stay alive for more than 1 - 3 turns) your Rancor becomes enraged, it would still target enemy units.