I think a smart home hub of sorts should be something you can install in any home, like a water heater or an internet router. The hub connects to your wifi and manages all of your smart devices. You register your devices with it using a web interface that is only just like configuring a router

The web interface part would be the really complex piece I think. You would have to have some way for devices to tell it what features they have, so it could dynamically produce the appropriate controls per device

I dunno if this is really feasible to actually build but it's one of the only ways I can think that would allow average non-technical people to do this without having to administrate their own hardware and network settings and such