>You're using a definition of “all of a sudden”

That is a fair point, assuming a person knows about the EOL. The article for this is "Support for OnHub routers ending in 2022". If that is the same email subject Google uses for email outreach (assuming they go that far) then it's something that many users would simply ignore, especially since the majority are nowhere near as security conscious as people here in the HN community. So I think there is potential for a sizeable % of owner to have "sudden" expenses.

your ISP is going to yank access due to an unpatched vulnerability.

If it's hardware I get through my ISP then they replace it. If it's not hardware from my ISP, how would they even know? I'm not sure that an uplink from the cable model to WiFi router will give them that info. And even if it did, they'd have no idea if I had simply slapped OpenWRT on the router negating the EOL issues.

I think you misunderstood the concept:

I'm talking about the people who would still want the device. Maybe a small portion, admittedly. My bigger concert is the moral hazard presented by giving OEM's an incentive to have ever shorter & shorter support windows. Just look at the CPU req's for Windows 11: Many millions of pre-8th gen Intel chips have the horsepower to run Windows 11. Just imagine how awful it would be if every system with an older chip had to be tossed in the trash.

Google never said they were offering lifetime support for OnHub and very few people would expect them to offer

That's a reasonable point. But in the vast majority of cases "support has ended" does not mean "your device is now (nearly) useless.".

For things like ongoing patches & similar maintenance, I understand that it can't reasonably go on forever. I do believe that vendors should have to publish their support horizons though. I'm not sure why you don't think this would help: It would tell users upfront, given that more & more of Google's products rely on their cloud support, when it will become a brick. I'm sure that folks who bought an OnHub 3 months ago would have appreciated knowing it would barely last a year.

With the Pixel this provides customers with a very useful piece of information when making a purchase decision. I know I take it into consideration: I just had to upgrade (dropped my phone-- no more crappy minimal cases for me now) and their support horizon was a factor in determining whether I went for a 5a or paid a little extra for a 6. (I chose the 6... better spec's, but I liked the style more too. :) )

So, I think expiration dates-- especially if more prominently displayed than with Pixel phones: think big bold Letters on initial config & an email where the use has to actively confirm receipt... some people will ignore and just click through, but they had their chance so long as Google doesn't bury it in a wall of text.

Still, your point about security vulnerabilities is well-taken. If there was to be any mandatory recycling, it would need be a very generous timeframe. It would be somewhat unique for consumer products, but safety limits on usable lifetime for equipment exist in various industries. I would want regulations to approach the topic with extreme caution though to at least minimize vendor influence.