As a part of our commitment to providing WoW players with a living, connected experience on multiple fronts, we are transitioning away from the current World of Warcraft Mobile Armory app and will be converting the Legion Companion App into a new WoW Companion App in the future. As part of that, we’ll be incorporating many of your favorite World of Warcraft Armory app features along with features for Battle for Azeroth into a new shared app for a more streamlined experience. Stay tuned for more information.
Source: https://worldofwarcraft.com/en-us/news/21901726/the-wow-mobile-armory-app-support-ending