Depending on how long I’m in our house (i.e. whether I think my kit has residual value) I’ll do one of two things:
1. If I move soon, I’ll probably do what Quentin did and take it with me.
2. If I won’t have use for the kit where I move to I’ll probably create a address and move the Evohome and LightwaveRF over to that. I can then leave a username and password for a functioning system and the new owners can do what ever they like with it.

Part of the reason I chose Lightwave and Evohome is that they function without needing to be connected to the internet and so guests don’t need training before using the house for 99% of the time the network capability is purely incidental.

Security systems, cameras etc are going to be a much bigger problem. But as someone who moved into a flat with an ADT alarm that was a massive pain in the arse before IoT came into existence anyway.