I've mentioned it before, and there are some fan stuff out there for these, too.
Zann Consortium
The Mining Guild
The Corporate Sector Authority
Hapes Star Cluster
I feel like the Old Republic / CIS and New Republic / First Order are things that can be done if done well. I for one am hoping for a Rebellion-style campaign system that allows for the transition from Republic -> Empire -> First Order as well as CIS -> Rebels -> New Republic
This campaign would be, IMO, a spectacular way to release CIS and Republic factions. It would even allow for players who only want to stick with one faction to play as well, as after a certain point in the time track (like in the Rebellion game) the Imperial and Rebel stuff gets moved in, and players from the early half of the game can decide which side to join afterwards or be split 50/50 and assigned, which would be more fair and not cause lopsided situations and would avoid any kind of political mechanic (even though that might be pretty fun too!)