This is a very significant change that has the potential to vastly alter the end-user Gmail experience. Even the service's incredibly helpful automatic categories -- such as Promotion, Updates, Primary, and Social -- will be disabled if you opt-out.
https://www.techspot.com/news/87623-google-soon-you-opt-out-gmail-data-collecting.html?utm_source=dlvr.it&utm_medium=blogger
https://www.techspot.com/news/87623-google-soon-you-opt-out-gmail-data-collecting.html?utm_source=dlvr.it&utm_medium=blogger