I don't understand what the problem with home automation is. Why does it need to be decentralized? You could have one switch station in the cellar, a small router running Linux would be fine. Then you connect that to a self-built electric autoswitchboard, connect a few sensors and cameras to the Linux box and do the rest in software. No need for proprietary light switches, but of course you need a separate wire for every light switch/bulb, a problem which can be solved by small "satellites" in each room, minimizing the need for extra copper. That solution is far superior IMO, you could for example trace the people in the house and only have lights in the rooms with actual persons in them, same for the speakers. Imagine, the music follows you!