Seems the real expansion name is "The Burning of Azeroth"
The XPac will feature the return of the Burning Legion.
"Since Sargeras true spirit was deep withing Medivh's soul, it managed to leach on the old God of N'zoth. Now
Sargeras spirit seeks to reach into the depths of the Emerald Dream via the Nightmare to open the door into the Twisting Nether
to re-unite with his true form in the twisting nether along with all his minions. Kil'Jeaden and other Eradar Commanders will enter
Azeroth to burn much like The Dragon Prince for told in the mists of pandaria."
"...The Dark Below was a hoax set out by blizzard to give out hints but also obscure the next expansion..."
"...Aszhara will be involved in the xpac as a raid boss along with an intensive quest line surround her and her past..."
"...Questions surrounding the disappearance of the Titans will be unveiled in this expansion...."
"...Former heroes not seen in the current lore will return such as Khadagar and the return of previously "Dead/Defeated" Foes/Allies..."
Leaks from a Blizzard Employee