NO new class
NO new race
All race models except Worgen, Goblins and obviously Pandaren overhauled
NO Alleria and Turalyon (at least not at release it seems)
Garrosh does indeed time travel back to a time in Draenor when the Orcs were about to drink the demon blood. How he gets there involves his trial, and possibly Anduin /Zaela Dragonmaw (don’t know details). He stops his father and the other Orc chieftains from following Gul’dan and entering the pact with the Legion, and takes over as Warchief (presumably). Gul’dan it seems is kicked out of the Horde. It seems he brings modern technology to reinforce this Horde in the past.
Apparently Gul’dan is just banished, and likely to summon the Legion on his own still.
Garrosh forms the IRON HORDE (yep), a Horde free of demonic and Legion influences, and begins to conquer Draenor. The WARLORDS OF DRAENOR are the Orc chieftains that follow him, including Grommash and many you know from the stories, with only Durotan, Thrall’s father, being good.
We travel here with the help of the Timewalkers to fight Garrosh apparently, how this is logically explained I don’t know yet and am hopefully learning right now from the trailer or the panel later ^^
This is Draenor of the past, not Outland. There are many zones from Outland as you know it, but completely redone and different, plus more zones that don’t exist in Outland later (including an Arrakoa only zone with cities in trees and the native continent of the Ogres). Hellfire is a jungle, and Garrosh is constructing the Dark Portal there. Ner’zhul is assisting Garrosh and apparently gaining his trust. Zangarmarsh is a sea full of mushrooms. Netherstorm is Farahlon, but not in at release it seems. Shadowmoon is more like Terrokar, uncorrupted and lush.
The Alliance capital is Karabor, which players later knew as the Black Temple.
The Horde capital is to the west of Blade’s Edge Mountains, in the Frostwolf homelands, a tundra. A former Ogre fortress it seems.
The main heroes are Velen, Thrall, Durotan his father, Vol’jin, presumably a Broken or Draenei called Masaad or Manaad, some dwarf and some Tauren. No word on Anduin or Wrathion, I don’t know if they come along but I assume so.
Some more juicy details:
The Iron Horde uses Gronn as siege mounts.
Shattrath, Auchindoun and some Orc/Ogre strongholds are the first raids (some may be dungeons).
There’s apparently some new tiger race.
Arrakoa have their own zone like mentioned above, possibly something being done with their Old God.

Personal assumptions:
I’m assuming level cap of 100, to go with the Garrosh heirlooms as well as to fit the leveling pace of Outland again roughly over 10 levels.
No idea on any other features or professions.

Biggest bullshit ive ever read

if what winkle says is true then the entire wowlore has been scrambled and this could become the worst expension ever created ><.. this would mean the orc wars would never happen on azeroth stormwind wouldnt have fallen, the darkportal itself wouldnt exist i bet garrosh himself wouldnt even exist lol. i doubt blizzard will make such a dogma failure