Wars are all fine and dandy, but what about the revolutionary factions that dot each house (Hellfire/Harmony, Hessians/Bundschuh, Mollys, Blood Dragons)? Supplement wars with more noticeable inter-house conflicts.
Ideas:
Blood Dragons finally take Tomioka (or launch a large offensive against such)
Hessians launch an invasion into New Berlin
Mollys coordinate with IMG to destroy Graves (seems like it was in the works, but idk where it went)
Legion attack Pennsylvania in coordination with Harmony
Farmers Alliance and LWB remnants coordinate to make Synth Foods' life hell
All of these could easily supplement any war between houses, adding to the fighting that could take place and the story development.
