For once I kind of agree with Snapple ... yup, end of the world
From what I've heard the economy of castles here is very crappy on account of Hero being different and making it very hard to keep a castle .. I think those that have actually managed to hang on to a castle for long enough to carve out a good economy shouldn't be screwed around like that.
And if you REALLY want to change up the castles then go for it, but give them back to the owners they should have and give them the economy they should have as well. It is only fair that way.