The trick is just to make all the automation optional. If I sell my house, I'll hand over my Lutron Hub and Z-Wave USB stick. If the new owner wants to plug those in to something, they'll have a bunch of entities to automate how they please. If not, it's just a house with a bunch of light switches like any other. Well, there are also some door/motion/humidity sensors, but it's not like they do any harm if you don't do anything with them.
