The Elite: Dangerous site has been updated with a brief note to announce that the game will no longer be supported on Mac gaming systems after the release of the Q4 update. Developers wrote, "Despite our best efforts, we have been unable to bring Elite Dangerous Horizons to Mac since launch due to technical barriers."
With the planned improvements coming in our Chapter Four update of the Beyond season we have felt it necessary to make this difficult decision in order to allow us to bring in content and features in the way that we felt was best for the overall Elite Dangerous experience. It is for this reason that we wanted to give you as much notice as possible. With the release of the Q4 update, coming towards the end of the year, you will no longer be able to play Elite Dangerous on Mac. As soon as we have a date of the update to share, we will do so here.
Read more on the Elite: Dangerous site.