This was also reported elsewhere few days ago, but Alaska looks to be the first one to update their partner listing with Oman Air/OneWorld membership..
https://www.alaskaair.com/content/mi...:partners-oman

Their premium Cabins, First (being discontinued/rebranded as Business) and Business are really great, with great service on the ground and onboard, but the standard in Economy drops considerably to the lowest level I have experienced on any airlines, including not securing properly the cabin for take off landing, where the crew walks around the cabin with no care in the world.