First, just on the topic of each faction, that's definitely never happening; even if we had all the access to staff and engine functionality in the world, most of the factions really aren't conducive to that kind of campaign- there's barely enough information for most of them to do the kind of events we're putting into 2.2, let alone a full story campaign.
Looking at just a smaller portion or a single faction, ie the New Republic, even just in the Thrawn Trilogy arc, it's not really feasible to do that, either. Anything involving animated cutscenes are definitely out the window. It's difficult enough to get the actual art assets for the mod done, let alone all the scenery and character models we'd need for that. On the whole, we're sticking to the kind of storylines within GCs that the NR has in Hunt for Zsinj, where they can recruit the Hapans, plus a handful of tactical missions like the Katana fleet one as part of that. Even for the somewhat limited scope that may seem, it's a huge amount of work. Even doing one mission/event per faction per GC comes to about 75 missions/events we need to script, and it tends to be a lot more than that. A lot of those are taking the things that translate into fairly obvious RTS missionlines, too; turning a narrative arc like the Thrawn campaign into a recognizeable and coherent campaign would be a challenge beyond just the technical aspects. Some of the New Republic's campaigns will play more like a "campaign" then before, but nothing quite as scripted as the base game's campaign.