There is a book in Skyrim that can be found in the living quarters of High Hrothgar titled "A Concise Account of the Great War Between the Empire and the Aldmeri Dominion". This book details the rise of the Thalmor and their conquest of various parts of Tamriel. It is an epic story, it is totally worth the read. It helps make sense of why there is a Thalmor Embassy in Skyrim, why the Imperials are working with the Thalmor, and it also shines some on the reasons why the Nords feel like their way of life is at risk. It would make an epic expansion as far as story goes, although it might require too much land to come as an add-on, it would be like the civil war quests but on almost every province, and on steroids.

heres a map

http://www.imperial-library.info/content/4th-era-tamriel-lady-nerevar

well they have to go with what they built right? so i agree with you they cant throw civil war in our faces and then make us sit around for another 6 years pondering what the sam hell happened to the thalmor. there most certainly has to be conclusion either one way or the other, or ill be one sad fan boy