Usually when a large company relies heavily on a cloud provider, they have an additional contract that specifies, among other things, advanced warning of any pending shutdown, often measured in years, to give them enough time to adjust and also to appease their shareholders and auditors.
And even without this, Google has a history of proactively notifying paying customers years in advance of termination of a commercial enterprise service. The Search Appliances are a perfect example -- EOL was announced a couple years ago but support has persisted for existing customers and only next spring will they finally be fully unsupported. Moreover, Google is actively offering migration plans & assistance to move GSA customers to the new Cloud Search service, or even to third party indexers like Elastic.
I get the gist of the OP's complaint, but like you said, that behavior pattern is just not tenable in the kind of operating environment Google Cloud finds itself in these days.
Disclaimer: I work for Google Cloud, but not on any of the aforementioned products.
