That is a good thought that has been suggested to them a dozen times over the last 6 years. It won't happen.
I have a good idea why since I know how a rohan server is put together.
Trust me the cost of changing their server deployment pattern will be far more expensive than they will want to spend on a game that is just barely breaking even. A lot simpler (and cheaper!) to add content, merge or add servers into the existing deployment structure.