So, before I get started I'd like to let readers of this thread know that first and foremost, this is not official WoW lore. This entire thread is based purely on me wanting to express how I sometimes imagine how the story of WoD would go for me ideally and for some of you to leave a few posts sharing what you think too. Secondly, I am no WoW lore nut, so I'm not even going to pretend I know the half of classic Warcraft lore. This is just based on what I do know and what I'd like to see happen. So please, if you enjoy reading this, let me know! If you want to speculate, post speculation here! Right then, let's begin.
In the post expansion patch/event, I would like to see a world event in which players travel to the Shado Pan prison to learn that Garrosh has escaped from his cell. A massive group of players must join Thrall and Jaina in pursuing Garrosh through a series of portals which will take them to various landmarks around Azeroth and finally to the a branch on the end of Teldrassil, where Garrosh throws himself off the top of the great tree and through another portal which closes upon Garrosh entering. Players will then face off against the Timewalkers' traitor before he teleports himself away from the battle. We see a short cutscene after the event in which Garrosh emerges from a portal on Draenor and is told by the Timewalker what he must do in order to conquer Azeroth. He then sets off on his mission to find and guide the Warlords of Draenor to an assault on Azeroth.
Warlords of Draenor:
Throughout the expansion itself's story, there will hopefully be lots of interesting developments and story twists that I would love to see players be a part of. These are some of them:
Upon arriving on Draenor, Thrall and a small party of orcs will travel to Frostfire Ridge where he will be reunited with Durotan, his father and leader of the Frostwolf clan. Durotan will welcome Thrall warmly into his clan and after some time, join the Horde. However, when Grom and the other orc Warlords learn of Durotan's union with the Horde, they will attack Bladespire Citadel. A battle will take place in which the forces of Horde and Alliance will repel the Iron Horde from destroying the home of Frostwolf clan, but in the battle, Grom faces and makes Thrall his prisoner. The Citadel is successfully defended, but Thrall is lost in the battle.
The Prophet Velen travels to Karabor and will meet his alternate self from the time before the city became known as the Black Temple, and the Alliance are invited into Karabor after helping Velen fight back Iron Horde invaders. Varian meets with the version of Velen from Draenor in order to offer the support of the Alliance in the battle against the Iron Horde on one condition, that his son, Anduin, be trained in the ways of the light to become a more powerful and capable priest, and that he is kept safe. Velen accepts, and the draenei and Alliance are united.
In the final battle against the Iron Horde, a party of heroes lead by Durotan or Khadgar will invade Shattrath City and topple the Iron Horde once and for all. During the raid, players will witness the reunion of Durotan and Thrall, who has been kept prisoner in Shattrath since his capture in Frostfire Ridge. Upon reaching the throne of Grom Hellscream, players will fight him until he becomes enraged and overpowers them. Before Grom finishes off the heroes one by one, Garrosh will charge into the fight. Having had enough of allowing his father to take all of the credit for the might of the Iron Horde and place Garrosh second in command of the Warsong clan, Garrosh faces and defeats Grom. Proclaiming himself new Warchief of the Iron Horde, a sword is driven through Garrosh's back and Varian is revealed as the killer. Durotan, Thrall, Khadgar and Varian will convene at the site of the final battle, and the Timewalker who first allowed Garrosh to escape Pandaria arrives. The traitor reveals himself to be Medivh, who has gained access to time travelling abilities. He announces that even he is not the most powerful being in the universe and that events have been set in motion that will see the return of his master, Sargeras, and the Burning Legion. Medivh will then exit, leaving the Alliance and Horde to clean up the final few Iron Horde forces on Draenor before finally allowing this alternate version of Draenor to exist in it's own timeline, without having been destroyed and turned into the Outland.
In the aftermath of the war on Draenor, Thrall arranges for a ceremony in which those who fell in the battle against the Iron Horde are honored, including Garrosh. Jaina witnesses both Alliance and Horde honoring the memory of Garrosh and protests against it, announcing that her Kirin Tor can no longer be a part of the Alliance. Varian asks Jaina why she is not happy that the Alliance and Horde are finally peacefully co-existing, and Jaina disregards Varian as Garrosh destroyed her home and her life. She accuses Varian of being a poor King and leader, and vows revenge on him and the Horde. Varian and Vol'Jin meet, and share their contentment that the Horde and Alliance are putting aside their differences for the time, and Wrathion shadily mentions to Thrall that his mission has been accomplished now that the Alliance and Horde are willing to fight side by side, and that Azeroth's darkest hour is coming soon.