Battle for Dazar'alor
The Battle for Dazar'alor raid opens after the weekly reset on 22 January, bringing three new mounts - two drops and one achievement reward. The chilly Glacial Tidestorm elemental drops from Jaina Proudmoore on Mythic difficulty only, and the G.M.O.D. golden mecha-suit drops from High Tinker Mekkatorque (likely on all difficulties). The raid meta-achievement reward is the Dazar'alor Windreaver, an armoured teal pterrordax.
Battle for Azeroth Season 2
Battle for Azeroth PvP Season 2 also arrives after the next weekly reset, and introduces two new Vicious mounts: the Vicious Black Warsaber for Alliance, and the Vicious Black Bonesteed for Horde. Earning one should award you both. Once earned, you can fill the bar again to receive a Vicious Saddle, allowing you to purchase a mount from previous seasons.
Also in this season, Gladiators will be vying to earn the blue Sinister Gladiator's Proto-Drake.