People complained, and Motorola listened. In a statement issued today, Motorola has promised to make good on its marketing and update the Moto G4 Plus to Android Oreo. Unfortunately, there is currently no time frame on when the update will be issued.
https://www.notebookcheck.net/Motorola-flips-again-promises-Android-O-for-Moto-G4.249358.0.html