I bounce off the notion of campaign arcs. That just doesn’t reflect anything that I ever use or even think about. It smacks of plotted courses through the setting material and I’ve no interest in that.
I have cartels in my settings, what most would call factions. I often have factions within cartels, so I reserve the use of the “factions” term for those internal groups. Large or small, I don’t pick and choose which cartel is going to have the most effect in any campaign, as what the players choose for their PCs determines which cartel sees more onscreen action. The cartels simply do their thing in the background if the PCs don’t get involved in any fashion, so cartel action can affect the setting without directly affecting the PCs.
I also keep in mind that major actions by any cartel are also opposed by other cartels and those cartels will take action even if the PCs ignore the first. There’e generally never a case where the PCs are the only possible source of response to cartel action. The world spins with or without PC attention; the setting isn’t focused on the PCs, despite the campaign looking at how PCs interact with it.