Battle for Azeroth Mounts
One of the many things that datamining has discovered is the huge variety of exciting new mounts coming to Battle for Azeroth. There are a lot of goods, and the best of them as below.
Brutosaur, hyena and parrots
Crawg, Goblin Hovercraft, Gilded Ravasaur and Tomb Stalker
Hivemind multi-seat mount.
All the new BFA features and content are on the two new continents: Kul Tiras and Zandalar, which are explored by the Alliance and Horde respectively.
You'll level on your own continent in gameplay terms, and then open up once you reach max to do world quests and continue the storyline. They each contain three zones, broken down as below.
Stormsong Valley - the place where Kul Tiran ships are blessed by Sea Priests. There are probably Old Gods here.
Drustvar - this area concerns a mysterious village and its frozen inhabitants.
Tiragarde Sound - overrun with pirates, as well as Jaina's mother Katherine Proudmoore. Likely the Alliance capital of the expansion.
Nazmir - playable at BlizzCon, this is a Blood Troll focused area where you defeat various spirits. It also has Old Gods in it.
Zuldazar - capital of Zandalar, and thus the Horde capital for the expansion. An uprising provides the narrative focus.
Voldun - a desert and prison for the Zandalari, it also has a race of almost certainly adorable fox people. Plus: Old Gods.
During this process, you can explains what's going on in the wider world through the War storyline.
Battle for Azeroth Dungeons
New dungeons (total 10) are also on the way.
Freehold - A pirate flavored dungeon in Tiragarde Sound’s the underworld.
Waycrest Manor - A stately manor in Drustvar, haunted by a Kul Tiran noble house.
Tol Dagor - The "prison island" of Kul Tiras.
Shrine of the Storm - Stormsong Valley's ship-blessing dungeon with Old Gods and sea priests. Siege of Boralus - Set in Tiragarde's capital, this is a max-level dungeon akin to Court of Stars from Legion.
Atal’Dazar - "undead dinosaurs" inhabit the troll-based dungeon in Zandalar.
Temple of Sethraliss - Vol'dun's snake-people temple.
The Underrot - this dungeon is where Nazmir is being corrupted from.
King’s Rest - An ancient tomb filled with probably not still dead kings of Atal'Dazar. Dungeon inception.
Kezan - The Horde max-level dungeon is the Goblin starting zone reconfigured, since the little green ones go digging for Azurite.
Battle for Azeroth Raids
Uldir, Halls of Control
Details are massively unknown so far, but it will have eight bosses: Harlan Sweete, Gluttony, Witch, T'zane, Taloc the Corrupted, Priestess Alun'za, Council o' Captains and the Blood God. It is an initial raid, so don't expect too much challenge.
The name is TBD, and it will involve eventually fighting Queen Azshara and her Naga.
Battle for Azeroth Allied Races
New races will be joining each faction.
Dark Iron Dwarves
In addition, it has also been said that Draenor Orcs will be an Allied Race too, suggesting that there are more races to be announced.
Allied Races start with their own questlines at level 20, and then transition into the normal levelling experience - supplemented from patch 7.3.5 onwards with scaling. If you get an Allied Race character to max level, and you will unlock a 'heritage' armor set unique to that race.