Do people have any faith in the these sorts of notices, when nothing ever produced by the company has yet been supported that long?
Absolutely. If they decided to make this announcement, I have faith that they'll stick with it. Whether Pixel 9, 10, 11 etc. will have similar pledges, we'll have to wait and see.
They're still honoring it - they're just not continuing the program after all current subscriptions expire. People who paid for it are still getting what they paid for through the end of their subscription, although because the program is not continuing, your subscription will end at the end of two years. In other words, the Pixel Pass was more or less equivalent to Google's existing 0% APR financing (which is still offered, including on the Pixel 8!). The only difference is that the Pixel Pass autorenewed at the end of 24 months, whereas otherwise you have to manually reorder the next phone with the financing offer[0].
That's different from not delivering the product/service that customers have paid for.
The promise of 7 years of updates is legally binding. If Google promises 7 years of updates, and then doesn't deliver those, that will be a violation of both state and federal law (California is now requiring 7 years of updates, and it is additionally a violation of federal law to advertise a product with a service, sell that product, and then fail to deliver that service).
[0] The 0% APR financing offer is actually now slightly better than the Pixel Pass, because on the Pixel 8 it's now amortized over 3 years instead of two (which is new - previously it was amortized over 2 years).