Blizzard has shared an article explaining how players can unlock flying in Northrend, once Wrath of the Lich King Classic. Wrath of the Lich King Classic launches on September 26, 2022.
Once you arrive in the frost-covered lands of Northrend in Wrath of the Lich King Classic ™, your mounts will get you where you need to go, but only on the ground. However, with Cold Weather Flying, you can conquer the biting chill of the Northrend air in no time, so bundle up and get ready.