Been thinking about this a little so feel free to offer your own opinions, suggestions, or who you'd like to see added as a commander or operative in the game for the OT factions. Heck even throw it out there if you prefer they are represented with a certain outfit or pose.
As a fan of cross play figured I'd first start with filling out the Rebellion Board Game (Base Game) Leaders.
Rebel:
Mon Mothma - Likely a weak physically commander that is good at dodging and evasive defensive play. And considering her role I could easily see her being released with some form of honor guard similar to Palpatine with his Royal Guards.
General Rieeken - Another defensive based commander, likely geared towards tanking hits with a focus towards holding points and stalling. And considering he was the commander at Hoth it would make sense to see Echo Base Troopers released alongside him.
Jan Dodonna - Now, I considering the Battle of Yavin I could see them tying him to being a buff to vehicle play, or heavies somewhat similar to Veers but at the same point I could also seem him as being focused on core unit lists.
Crix Madine - As he was in charge of the special forces it would make sense that he gave some sort of buff to them, with his command cards buffing them or helping set them up for an impactful round.
Wedge Antilles - A commander built around buffing vehicles, especially repulsor craft, with a command card to represent an air strike. And hopefully with him being released with Rebel Pilots...I just really want Pilot minis.
Admiral Ackbar - It could easily be argued that he doesn't have a place on the battlefield though he was known to be on the ground for fights in canon like the defense of Mon Calamari from the Empire, and serving the king in Clone Wars. Besides he could likely be a counterpart to Thrawn of sorts.
Lando Calrissian - Now here the question is if he would be an Operative or Commander since I could see a case for both. As for gameplay I could see them based around gambling, high risk/high reward though I'd wonder if that might just make him not too common at higher levels of play.
Obi-Wan - We will definitely get him as a commander for the Republic faction, and it could easily be argued that he shouldn't be in the game for the Rebellion considering his role in the films. If he did get in at best I could see him as an Operative for the Rebellion.
Luke/Leia/Han Solo - Yes we already have them but it would be great if they got Operative variants down the line just so people could make a standard game army with all three included. And Luke would be a prime candidate for the ROTJ Jedi treatment.
Imperial:
Tarkin - Its really only a matter of time until we see him added considering his iconic status and the fact he was shown to be an on the ground commander in Rebels. His command cards likely all geared around heavy oppression and suppression.
General Tagge - Not as highly remembered but has been shown off a fair bit in the Vader comic, and later becomes a Grand General after the Battle of Yavin. Lets just hope his Legion version is better than his Armada version.
Soontir Fel - The Imperial Counterpart of Wedge, and like with Wedge hopefully Imperial Pilots would be included with him. Ideally having something like his pose in the WOTC minis game could be used with him holding his helmet in his arms.
Wulff Yularen - Another candidate for the Republic faction, granted one that would likely be pushed down in priority in the metric ton of Jedi characters, but he was the head of the ISB. It would be interesting if his command cards had to deal with information, maybe even one of them forcing your opponent to show their hand of command cards, likely for a turn 1 command to know what you are dealing with moving forward.
Admiral Piett, Admiral Ozzel, Moff Jerjerrod - All rather iconic, though officers that served aboard Star Destroyers and the Death Star so not sure if they would be included at all unless FFG doesn't have access to another commander.
Janus Greejatus - HAHAHAHAHA No...just no. I can't see FFG dropping a dignitary/Palpatine groupie as a commander or operative.
Honorable Mention - ESB Bounty Hunters (Bossk, Dengar, IG-88, Zuckuss, and 4-LOM) I suspect they will show up at somepoint considering how Boba is already an Imperial Operative.
Next up the animated show, Rebels.
Rebels:
Hera - An obvious Rebel Commander, likely with a focus on hit and run tactics considering how the Ghost crew tended to operate.
Kanan - Not sure if he'd be a Commander or Operative, on the one hand Commander would allow for more of the Ghost Crew to be added into a list though he never really led anything and was more an Operative overall. I do think he'd have some ability that plays well when being around Ezra, and if he was an Operative he could likely have Command cards meant to boost the others in the Ghost Crew.
Ezra - Same as Kanan though, in regards to Commander vs Operative, though as he did hold rank and led a few missions for the group he could be considered a Leader I guess. I imagine he'd be more of a budget Luke, with a weaker overall saber, and less Force Upgrade slots.
Zeb - I think he'd be like a 'Rebels show' version of Chewie, in that he'd be an Operative and have some sort of ability similar to Chewies with Han that either lets him play well and boost specific Ghost Crew characters or even have it so that those with a certain subtitle like Spectre or Ghost Crew to get the boost
Sabine - Definitely an Operative, with tons of weapons and options, her command cards like Boba's being weapon based. In her case they would likely be demolition based.
Ahoska - Again, definitely an Operative, maybe considering she has two light sabers she could either perform 1 strong attack or 2 weaker attacks. A trade of damage for removing tokens + giving suppression.
Rex - Arguably he is already in the game as one of the trooper minis in the Rebel Troopers pack, but I guess they could add him as an operative if they wanted to as well, since I don't think he really led anything for the Rebels.
Imperial:
Grand Admiral Thrawn - I think it is only a matter of time before we see him added, he is too popular and could be interesting if he had some command cards that played towards outsmarting or outplaying your opponent to some extent rewarding people for playing well.
Kallus - If they were to do a cross faction character he would make sense, and could be done as an Imperial Commander and a Rebel Operative.
Inquisitors - I could see them releasing the Grand Inquisitor as a Commander or Operative but at the same time FFG could easily just release a Special Forces expansion with them as a generic light saber unit, so I guess sort of a more expensive Royal Guards.
And finally Rogue One.
Rebels:
Jyn Erso - She is another one of the Commander vs Operative cases, she wasn't really a member of the Rebellion and only really was involved in a couple missions spanning a couple days so you'd assume Operative but she did sort of leader the mission to steal the plans so maybe Leader? Really not sure, just hope they'd use her good FFG art, X-Wing 2.0, instead of the older one used for X-Wing 1.0 and Armada.
Cassian - I see him being an Operative, but really they could play with it how they like so that at least Jyn, Cassian, and K2 could all end up in a single list. I'd imagine his command cards though would do with intelligence or the like to spy at the opponent's hand.
K-2SO - An Operative, and like Zeb and Chewie one meant to boost certain characters, in this case Jyn and Cassian.
Baze - Heavy Operative that can doll out lots of damage and not really do all of a heck else, aside from having some bonus effect with Chirruit.
Chirruit Imwe - I'd say he'd be a Melee based Operative but he does have that crossbow blaster that he whips out a couple times. Not sure if they should implement the crossbow to be powerful but hard to shoot since well he was blind and is obviously meant to attack with his stick or to make it accurate and damaging since it took out a Tie Fighter but have some ability to make him deadly in Melee combat.
Bohdi - I really don't know, he was the most forgettable out of the group for me, maybe just make him a pilot upgrade?
Saw Gererra - Likely a Commander, released alongside Partisan Rebel Troopers. I guess they could make him built around being a single commander, one that doesn't play well with others.
Imperials:
Krenic - I'm pretty sure we all think it is just a matter of time until he shows up, likely being released alongside Death Troopers.