How about trading ??
They are going to implement a way to change locations, but how about sizes too ??
I'm guessing it will work like this:
Lets say you own a small house in the goblet, with furniture and all. Then you wanna move to lavender beds, so you find a small empty plot, attempt to buy it, and you are prompted if you wanna move your house in the goblet. You say yes, and all your house settings are transferred intact. Kinda like a cut and paste.

The problem would be for example moving a large house to a small one... the new house won't be even able to hold as much furniture, how to decide which stays and which is gone, right?

HOWEVER, those who don't use their houses will be getting 80% of their money back and all the removable furniture stored with an npc.... that is 80% better than abandoning !! (in which case you don't get anything back and still have to have enough room to store all your furniture somewhere).

So why not combine both ??

When you own a house and try to buy another plot, you are asked if you wanna move. 80% of the price of your current land would automatically be used to pay the new plot, the change will be given back to you the same way that expired plots would. Then, your old house will be destroyed just as an expired plot would, and all of your removable furniture will be given to the npc, so all you have now is a new empty plot ready to develop.

So lets say you move from a small house to a large, and you paid 2m for your house. The large plot would then cost you 1.6m less than it would to someone who doesnt own a house (80%, right?). You will still lose your levi fountains, airships and whatnot... but still, is MUCH, much better than having to abandon and get nothing in return, yet still have to payfull price for the new plot and deal with invevtory issues D: