I'm a non-native speaker and sunsetting is not clear to me. I guessed what it means because I know Google and how popular Google+ is (in relative terms, I'm sure there's still hundreds of thousands of people who will lose contacts over this), but if someone had said Cloudflare is sunsetting, I'd just not have known what it meant.

And even knowing what it means, as I do now, I wouldn't say that sunsetting is any clearer in communicating that it's "going to" end than "shutting down" or "stopping" Google+. It's not as if the proposal said "ended" or "shut down" Google+, the "are" in something like "We're shutting down Google+" signals continuation to me.