I was thinking the other day about them adding upgrades for the castle. For example a extra island or more room in the castle. It is more like a expansion to your house or castle. Foe houses that require you to craft they can make epic expansions or minor expansion. I hope you like my idea.
This would be really cool, since the house limit is set so low this would be a way to have more room and still fall within the house limit. The only problem I can see is that the item limit would have to adjust also or you would have more room but they would be barren, or much less adorned than the houses as they are now.