Expansion ideas

It was rumored that there would be 5-6 expansions to the world of Azeroth, mentioned in an interview by a leading person within Blizzard ("We have made concepts for this expansion, and we already have enough ideas for 5-6 more").

Below are ideas by users where future World of Warcraft expansions could possibly visit after World of Warcraft: Battle for Azeroth, the latest announced official expansion. The following are undeveloped regions that have enough content for an expansion pack. These ideas are grouped geographically:

The Emerald Dream

 * Related areas: Emerald Dream, Emerald Paradise, Emerald Nightmare, lesser, unfinished Emerald Dreams.
 * Possible new hero classes: dragonsworn, spirit walker.
 * Related intelligent/playable races: Children of Cenarius, sprite, furbolg, treant, dryad and satyr.
 * Related opposing forces: The Nightmare, Druids of the Nightmare, N'Zoth
 * Nethaera says: "As for the Emerald Dream, there are no plans for anything as of yet but it is a consideration for the future. The Emerald Dream opens up a lot of different opportunities and the Burning Crusade is definitely not going to be the last of the expansion packs. There are many different places and storylines that can be pursued. The story is going to keep growing and as it does so, people will get to experience it."
 * Metzen said: "The Emerald Dream is a nice idea and the team has talked about making it into an expansion many times. Building an entire expansion worth of zones around a green lush forest theme would get very boring, so the Emerald Dream would be better used as raid, dungeon, or a subzone, not an entire expansion."
 * Possible extra stuff: Spirit mounts you can use while corpse running, portals and/or shortcuts to several places in the world. Lore states that powerful druids can obtain supernatural abilities in the Dream, unknown if playable druids are powerful enough.

The Great Sea

 * Related areas: The Great Sea, South Seas, Maelstrom, Nazjatar, Mak'aru, Tel Abim, Plunder Isle, Gishan Caverns, Zul'Dare, Crestfall or Balor.
 * Return to Kazan/Undermine or Lost Isles.
 * Possible lands: outer islands of Broken Isles or Kul Tiras, zandalari islands outside Zandalar or previously undiscovered lands.
 * Possible new hero classes: Steamwarrior, techslayer, sailor, pirate, buccaneer, tinker, potion doc, and primal.
 * Related intelligent/playable races: Murlocs, makrura, naga, ogres, half-elves, and high elves.
 * Related opposing forces: Naga, Queen Azshara, and her underwater army. Perhaps also the Elemental Lord Neptulon the Tidehunter. Underworld Minions. Mur'gul. The Stormreaver clan remnants. Some of the other forces in the Great Sea are the Bloodsail Buccaneers and the trolls of Zandalar.
 * Possible extra stuff: Underwater mounts, Underwater dungeons / raids, Swift Aquatic Form (maybe its a shark/penguin), Boat mounts.

Underground Azeroth

 * Related areas: Underground Azeroth (Barrow Deeps, Azjol-Nerub, subterranean Khaz Modan, other underground regions).
 * Possible new hero class: Runemaster
 * Related opposing forces: N'Zoth and the Twilight's Hammer clan
 * Related professions: Faiths
 * Related intelligent/playable races: Troggs, titan-forged, kobolds, elementals, nerubians, Dark iron dwarves, naga, faceless ones, and qiraji.

Ancient Kalimdor before the Sundering

 * Related areas: Ancient Kalimdor before the Sundering. (Accessed via Caverns of Time)
 * Related opposing forces: Highborne, satyr, Burning Legion, Azotha (primitive humans) aqir, trolls, and infinite dragonflight.
 * Related intelligent/playable races: Earthen, furbolgs, Ancients, demigods, night elves, sprites

Old Horde/Alliance Wars

 * Related areas: Lordaeron, Dalaran, Alterac, Quel'Thalas, Old Draenor, Gilneas;
 * Related opposing forces: Mainly Horde/Alliance battlefields; (see: First War, Second War, Beyond the Dark Portal)
 * Related intellegent/playable races: ogres, goblins, forest trolls, Wildhammer dwarves;
 * Related enemy bosses: Blackhand, Lothar, Khadgar, Ner'zhul, Sargeras, Alexstrasza, Deathwing, Orgrim Doomhammer, Zul'Jin;

Great Dark

 * Related areas: Other planets besides Draenor and Azeroth.

Return to Argus

 * Related areas: Return to Argus, the eredar homeworld.
 * Related opposing forces: Burning Legion, unknown others
 * Related playable races: Broken
 * Related opposing races: felguard, eredar, and infernal
 * Related enemy bosses: Void or return of Kil'jaeden, Sargeras
 * Possible extra stuff: Guild spaceships, Exodar-looking.

Twisting Nether

 * Related areas: Other parts of former Draenor, because it is said that Draenor was much larger than Azeroth, so it is probable that Outland is not the only inhabited part. And maybe portals to other worlds that Illidan sealed.
 * Related opposing forces: Burning Legion, The Void, maybe some new currently unknown faction. Gul'dan's surviving death knights.
 * Related playable races: Broken, arakkoa, and ethereal.

Miscellaneous ideas

 * K'aresh
 * Xoroth
 * Other portal gates.
 * Other side of Azeroth.
 * The Fall of Silvermoon in Caverns of Time.

User expansion ideas
''We welcome users to be creative and add their expansion ideas per policy. After your idea has been added in full, feel free to link to it on this page. Please use the subsection most relevant to your expansion idea's theme.''

When you add your idea use the template,  and remember to help keep the list organized by placing your idea in alphabetical order (by user name).
 * This template assumes you created your expansion idea as a sub-page of your user page.
 * Example:

🇨🇴

General
🇨🇴

The Emerald Dream

 * World of Warcraft: The Age of Nightmare by Lon-ami.
 * World of Warcraft: The Age of Nightmare by Lon-ami.
 * World of Warcraft: The Age of Nightmare by Lon-ami.

Deathwing/Old Gods

 * World of Warcraft: Whispers of Madness by K1tty
 * World of Warcraft: Fall of Twilight by Lon-ami
 * World of Warcraft: Whispers of Madness by K1tty
 * World of Warcraft: Fall of Twilight by Lon-ami
 * World of Warcraft: Fall of Twilight by Lon-ami

Lich King/Scourge

 * World of Warcraft: Whispers of Madness by K1tty