News Samsung reportedly preps the world’s first 500 Hz 27-inch OLED gaming monitor — sources allege 1440p QD-OLED panel

As I noted a year or so ago: OLEDs aren't really limited to any specific refresh rate given their near instant pixel response times. It was only a matter of time until someone decided to push refresh rates to the moon (EG: bothered to make a controller that can handle it).