In a new research note written for TF International Securities, the tech analyst Ming-Chi Kuo has stated that he now believes that Apple will switch to micro-LED for its sixth-generation Watch. In the meantime, the Series 5 will stick with OLED screens, albeit those from a new supplier. These devices may be launched alongside the iPhone "11" line later this season.
https://www.notebookcheck.net/Apple-Watch-screens-may-step-up-to-micro-LED-but-not-until-2020.430892.0.html