Speaking of the Princess...
Should I start fleshing her out a bit more and having her appear in scenes more often? I haven't been doing so on purpose, because I didn't want to step on anyone's toes should Erik die and someone take control of his sister. But it seems like it might be a good idea, if only to give nobles a better look at one of the people they could potentially support for succession if Erik did die.
And while marrying Drua would be slightly advantageous tactically, from the Miring situation, I doubt it would help much at all. She's also (probably) too low-born for Erik to marry her without causing a big uproar.
As for what the civil war changes? I guess it depends on the outcome.
Filius just said that Kain is likely to support Kara. I have a hunch that Grand Master Black would remain loyal to Erik's line and do the same. That's the church and a portion of the Eelspine range, as well as the internal spy network on Kara's side.
General Kaguro, who has a relation to the throne, would likely either side with Kara /or/ make a bid for the throne using his marriage to Erika. I highly doubt many people would side with that though. Of course, there's always a chance Sir Taric will side with Kaguro simply because Erika is on Kaguro's side and they seem to have a thing going.
Terenos seems to be fairly noble, and I think he'd maybe side with Kara in which case Kara's side immediately wins, giving Kara a pretty big advantage in the form of a capable assassin and (potentially) Preston.
I don't know what's going to happen to Miring, so I can't say anything about their role in a civil war should Erik fall, but I think a major deciding factor will be what outside sources do. Will Jarl Manskinner get involved? Will the Archbishop of Suul attempt to reestablish his faith's power? Will Brighthall get involved? How will the Ztah react? The people of Preston?
Will the people of Preston rebel, negating any advantage that a side might gain from having its Duke side with them? The Ztah raiders would no doubt take advantage of the situation, draining the land and its people of resources. I doubt Brighthall would even get involved.
But whichever side Manskinner gets involved with would have a pretty big advantage, and if Suul gets involved the civil war could end up being a staging ground for something far larger. It could well be that Erik's death has the potential to usher in a small age of chaos.