Now that there is a bigger building, it would be really useful to be able to remove Cabins to make place for the new buildings.
I know you said that there are problems to handle what will happen to things or persons that are in the cabins while theyre being destroyed, so how about this (temporary) solution.
In order to destroy the building it has to be completely empty. Every tick of destroying it should be checked if it is still empty, people that are logging in inside the cabin abort the process. The cabin itself doesnt show noticable decay (it doesnt get red). Once you reached the final tick the cabin is removed, and any char that has logged out inside it has to login at his hearth or idol or rob (like if you logout and something blocks your place).
If the cabin has had a cellar, you need a clay or soil in your inventory for every tick of destroying (to fill the cellar).
I know its not perfect but it would work.