Heyo, Alino here!
So I assume we'll see more than Rebels and Empire eventually. (I mean, this is supposed to be a miniatures game, afterall, so it'd make sense to eventually bring in more factions)
And so it got me wondering how they'd bring in new factions. I've got my Army in a box idea thread from awhile ago, but those were just ideas for bringing in smaller groups that don't have much variety (Can see the thread here - https://community.fantasyflightgames.com/topic/264286-army-in-a-box-sub-factions/ )
So I was thinking there's 3 ways they'd go with this.
1 - A Scum and Villainy Faction.
This seems like the most obvious choice, if they're wanting to stick strictly to the Galactic Civil War Era, although i'm not sure i like the idea of cramming Hutt Cartels / Black Sun / Mandalorians / ETC all into a single faction
2 - Prequel Era Factions
This seems like another direction they could take it, via introducing a Legion box for Separatists V Republic, and I can see each of these factions being quite different from Rebels and Empire. However, I know quite a few of the people playing this game are from the older generations of star wars fans that despise the prequel trilogy, so i'm not sure how good of an idea it'd be to introduce these guys. (I personally love the Clone Wars, but I have a feeling that in the Legion community, I'm in the minority)
3 - Sequel Trilogy Factions
I think if they go to either of the other trilogies in terms of factions, they'd do this one. That said, I'm not sure how they'd differentiate Rebels and Resistance. In my eyes, First Order would be a more elite Galactic Empire faction, with less models per unit and a stronger focus on special forces units (such as First Order Flametroopers and the like), although with the Resistance.... I guess Resistance could sorta be a faction that uses primarily small squads that are cheap (so cheap / small squads) but are really customizable (Or erm, as customizable as Legion allows), although ya know, it's just tough to differentiate them from rebels.
Anyways, those are just the 3 ways I see them going with this. And I think no matter what we'll probably get some form of Scum faction.