Patch 7.3.5 Mounts
We're aware of a few new mounts in the latest patch:
A pair of handsome foxes has been added to the growing catalogue of Vicious PvP mounts. These mounts may be purchased with a Vicious Saddle, which is earned through seasonal (Arena) Combatant activities. The Horde's Vicious War Fox is decked out in iconic Orgrimmar red with spikes.
The Alliance version of the Vicious War Fox sports traditional Stormwind blue-and-gold armour.
Finally, the Black Qiraji War Tank has apparently been awarded to players who previously earned the Scarab Lord title. This title has not been obtainable for many years, and was only ever earned by a small number of players during the opening of Ahn'Qiraj, mostly during Classic. This new mount model is shared by the silithids that appear in Silithus after the wounding.
Armory update issues...
A small number of mounts (approx. 9) are still missing from the official Armory and so require manual updates to your collections. These include the Felsaber, Chauffeured Mechano-Hog and Acherus Deathcharger, as well as six old and retired mounts from Vanilla. Sadly there's nothing more we can do until Blizzard adds them. See the forum thread for more information.
New Mounts(Patch 7.3.5)
Upcoming Mounts(later patches, or uncertain release date)
Mounts Coming in Battle for Azeroth
The list below only includes mounts that have already been assigned spells.