Dunno, from the outside it looks like internal problems killed Eston, not CE. From the outside it has often looked like Eston was filled with internal strife all through the war.
It certainly did, and that was certainly the case. However, the strife never had anything to do with "surrender" or "don't surrender." The Rieleston secession certainly hurt Eston and its ability to fight the war, a lot. However, even if Barad Riel had stayed with Eston, the result wouldn't have altered much. It was only a matter of time before Eston could no longer hold the stalemate, as we have now seen. Especially once Darka started telling Eston they could only commit 10k CS to defend Eston.
Darka on the other hands has been very stable internally for a long time. If the king says we fight until we die then that's probably what will happen. The dukes are loyal and over all I'd say we see death of Darka as a better option than signing the sort of terms Eston did.
This is probably because Darka has never been under any threat or pressure in a long time. There's no catalyst for internal conflict. It is no coincidence that the biggest instance of internal strife in Eston in several years came during the tail end of this war that it was becoming more and more apparent would end badly for Eston. External conflict breeds internal conflict.
That being said, Darka is pretty gung-ho about themselves and are pretty convinced their military is as best as it gets. So you're probably right, they might slug it out til the end. And good for them, I hope they make it miserable for CE & Co.
If we die we'll just take our gold and go take over Talerium or some other place that votes often 
Show up in CE. Elect KK the new Prime Minister. This has been the ultimate scheme of the Northern Alliance all along!
