An admittedly expensive solution would be to use the Ethereum main network to communicate with the IoT device.
For example, a local administration page that can be accessed within the LAN, and which can then be proxied by the provider. In the case that the provider goes out of business you lose the remote control (unless setting up your own VPN) but the device won't be bricked.
Unfortunately, I imagine some companies intentionally avoid doing this to require customers to pay a subscription fee.
I think we'll start to see regular consumers harmed by some of these start-ups destroying hardware when they go out of business, and perhaps people will stop buying them unless there's some protection. Then the "free" solutions will be looked at suspiciously and hopefully discounted by the tech press and retailers. Alternately, retailers might be held liable for refunding purchases of products that stop working before the legally mandated warranty date (such as in the EU) or by credit card companies in the US, so they'll stop selling any cloud required garbage.
Also remember that if you’re maintaining the hub yourself it won’t get security updates.
I think consumers need to understand that when they buy a connected device, they are also buying a license to the software that powers it. That license is generally not perpetual unless specified.
I'd love to see someone provide a pre-packaged zwave/zigbee talking home assistant appliance with support for snips.ai voice control. Unfortunately, hardware-wise it would probably cost $250 to build out of off the shelf components, but perhaps at scale it could be affordable? Google and Amazon are selling their closed, cloud chained voice assistants for practically below cost, though, so I don't know how such a product could really compete.
Sadly the "IoT" market is practically predicated on selling some hideously expensive service that you don't want or need on top of a piece of hardware that would be perfectly happy working against a home edge gateway rather than "the cloud". Approaching a VC asking for money for digital lightbulbs and dimmers that work against a local server running on a Wifi-router-like-box? Using a standardized protocol, so you don't need 10 different home edge gateways to orchestrate different tasks? Get out, we don't even want to hear it...
Accessing the Internet should add features - not having the Internet should not burden or brick the device.