Nest hardware will still work just fine?

I'm not sure where you're drawing the conclusion that the Nest Hello no longer works.

Not sure about the "Hello" but this sucks for people that take advantage of their thermostat API. The hardware still works but the way I use it won't any more.

Pretty much straight up FUD. This is not bricking Nest devices.

Ok, more like “That remotely controlled car with integrated taxi service you bought?”

Well, now it’s “Just a car”

For anyone using SmartThings, HomeAssistant, Hubitat, IFTT, etc., it is removing huge amounts of functionality.

I've been very happy in general that I switched to ecobee when I moved, and this made me even happier.

That would be a very large piece of paper!