I think if these projects were branded as Google Beta, or under Google Labs, people would be less disappointed when they get shut down.

I agree wholly here. Google needs to be much more upfront when floating experiments. It's good that they do, but the signaling needs to be better. Or even different branding altogether. It would go a long way to help their image.

Gmail was in "beta" for years and years, I don't think this would actually solve anything.

There's a difference between that and what Google does. Look at how many products on https://killedbygoogle.com/ that were several years old, e.g. AngularJS (11 years). And I'm sure many of us remember Google Reader.

To be fair AngularJS has a successor in Angular and thus is a bad example. I think it is fine to drop it after 14 years of support (which is almost ridiculously long in JS-time)

Omg, it also turns out that the Linux foundation killed Linux 3.0! How dare companies stop supporting old versions of their software!