How much would support increase when manufacturers realise how few of their TVs don't get connected to the network?

Even if it did support it, nobody connects their TV to their local network via HDMI, they connect it to their PC. And, as far as I'm aware, no PCs automatically start sharing networking with whichever networks they are connected to.

That could of course change. Could be even a nice feature for connecting your TV to the network via your multi media center, if the bandwidth is good.

LG was caught abusing (although it's hard to argue that it isn't intended behaviour) Windows automatic installation of hardware-related software to install adware. Doesn't take too many tinfoil wraps around one's head to imagine them doing the same to enable network sharing (assuming hardware support is ubiqtuous enough).

https://www.techspot.com/news/113031-lg-alienware-monitors-c...

Their solution to that is to either use the cell phone network or services like amazon sidewalk where they connect in through your (or a neighbour's) internet-connected device.

I think it’s also possible to piggyback on other devices signed with the same certificate to exfiltrate using BLE. Maybe I’m wrong though.

Then you make sure to only use HDMI cables that aren't HEC, in conjunction with not connecting the TV to the internet directly, if you want to keep them isolated.

If people really start not connecting them. TV makers will just start including a cellular modem.

Not at all, because it uses the same pins as ARC, so the two features can't operate at the same time, and a lot of people use ARC to get audio from TV apps back to a soundbar or receiver.

HDMI Ethernet is dead, it's never going to happen in consumer televisions because it has a hard conflict with a feature a lot of people actually use.

Proportion of HN users whose TVs don't connect to the internet? Significant

Proportion of non-HN users whose TVs don't connect to the internet? Negligible

Not even game consoles, PCs, even Raspberry Pi don't support it. Which is odd, so there are probably reasons why it's not worth the troubles.

Support in cables is nearly universal, because the same pins in the cable are used for the Audio Return Channel feature that allows a TV to pass audio from its internal apps back out to a soundbar or receiver via the same HDMI cable it takes signals in on from other devices. As far as I'm aware no one has made a cable lacking those pins since 1080p was still the high end.

But yes, support for the ethernet mode as far as I'm aware was never actually implemented in any devices that reached retail availability.