I have to disagree with you on the spirit of the game as you've implied it. The spirit of the game isn't keeping something alive until you're fully ready to let it go. This game is about battling through thick and thin - as you would in reality - while having a blast in the process - quite unlike reality.
Niselur, Asylon, and Barca haven't died yet. In fact, said realms have quite the potential to live on. What's ridiculous here is that a collection of people believe their realms can only retain their identities by inhabiting their current geographical areas. Get a grip, the necessary components to a realm are its nobles and the histories they create. Its regions come secondary. Sure, you've fought long and hard for Rettleville, Gaston, Gelene or Golden Farrow, but these regions don't define your realms. Generally speaking, what defines Niselur is its capacity to challenge, and subsequently overcome SA imperialism where it reigns strongest; what defines Asylon is its unique collection of nobles and beliefs: former obnoxious standout turned continental superpower; what defines Barca is its formidable resilience in the face of abominations (monsters and Aurvandils both): it survived when no one else thought it capable. Every last one of you have invested your hours creating these kind of achievements, histories and legends.
The same cannot be said about Rettleville, Gaston, Gelene, or Golden Farrow. These regions were created by the Devs, and shall remain long after your realms have run their natural courses.
So yeah, you're probably going to lose your current regions. How is that functionally different from your typical, total conquest? And if you've spent countless hours developing your realm, what's a few more in an effort to secure its future somewhere else? You might even have fun in the process! Look at the many kings and nobles of old who migrated, went into exile, or conquered other lands after their homelands were threatened or destroyed. They strove to survive, and so should the rest of you. You haven't lost anything yet!
