SE did say at one time that they were going to implement something that would cause a house that went unused for 35 days to disappear and free up the lot for a new buyer. However, there was such an uproar about it here in the forums that they decided to back off on that idea. They have yet to announce any kind of a replacement for the feature. So for now, you will not lose the house at all.

You should probably keep a watch on the Lodestone and these forums while you are on break just in case SE announces something different.