I have been kicking around the idea of using the Isaac Asimov Foundation series as a back story for a new set of factions. Importantly, I want to use as much of the starfarer story as possible, so my idea was essentially to insert the Foundation, and Empire factions, into the already existing collapsed society of Starfarer. If you've read the books, it's a good fit. It would look something like this.
Foundation (early)Before complete collapse
Large ships with mostly Ballistic weapons and awesome flux control.
Foundation (late) 400 years after collapse (I know, the timeline doesn't fit starfarer)
Smaller ships, super well armed with energy/ballistic combos. super fast.
Foundation (Epoch) 600+ years later
Super small ships (cruisers in destroyer hulls and such). Alarmingly advanced weapons and flux and engines. (have to find a weak spot to insert here somewhere).
Empire (early) pre-collapse
SHIPS OF THE LINE Massive ships with mega armor and huge guns. Slow and powerful (kinda like heg ships now).
Empire (late) After collapse
The empire ships of the line have been hacked up, refitted and sent out to fight again. New weapons, some new engines, maybe even a shield generator. These ships are kinda similar to junk yard ships in that they are pieces of other ships all mashed into a working new model. Sometimes they work, sometimes they don't.
Empire (2nd empire) 1000+ years later
Effectively take Epoch era Foundation ships and make them HUGE. The kind of absurd ships that could only be built be a star empire claiming millions of worlds and their resources.
At least, that's the rough plan I've been thinking on. If anyone wants to use this idea, I give it to you freely. If you want to do the art, while I help with the rest, I'd be interested in an arrangement like that too.