> Why would you need an update? Updates are mainly necessary for security, which you don't need if the device isn't on the Internet.
You've never had a problem which was fixed by an update or something which added support for, say, a new model peripheral? I have, which is why I allowed for the possibility of wanting to do this on the schedule of your choosing but not the default case.
> I don't see how it's a losing game if you play it correctly. Fine grained policing of types of traffic is a losing game, but wholesale denying transit isn't. There is little difference between my network of tp-link bulbs and say a local modbus network.
I was thinking less narrowly than devices which never need to be online. A TV connected to other players can run entirely offline but there are many other things which legitimately need connectivity and there's no good way to prevent that. For example, think about a device like a Chromecast or Fire TV, or those Facebook video chat appliances — people buy those to stream content so the most you can do is force the vendor to send marketing stuff through the same endpoint they use for your content, and that's increasingly hard to filter (think how useful a “it goes to an IP in AWS. Block y/n?” prompt is). That's why I said it'll require a legal fix since a large fraction of the most invasive devices either already do or could trivially be modified to mix other data in with the traffic needed to function.