So yeah, 7.0 arrives on July 19th, which is this upcoming Tuesday.
Let's do a quick recap of what to expect:
Class and Spec Changes:
I feel like I say this with every expansion, but most classes and specs are seeing some very big mechanical changes. Survival Hunters are going to become a melee specs. Combat Rogues will now be Outlaw Rogues with a clearer Pirate theme. Many DPS specs are getting new, non-mana primary resources: Shadow Priests will get Insanity, Balance Druids will get Astral Power, and Enhancement and Elemental Shamans are getting Maelstrom. Protection Paladins and Holy Paladins will no longer use Holy Power while Mistweaver Monks and Brewmaster Monks will no longer use Chi. Death Knight Runes are all just Runes - no more Blood, Frost, or Unholy Runes. Hunter Focus now regenerates faster on its own, and all three specs have gotten big changes to their rotations. Discipline Priests now focus far more on the Atonement damage-to-heal style, but they will need to actively ensure that their allies have the Atonement buff for them to receive this healing.
Really, only a handful of specs are coming out of this without significant changes. Expect to spend a bit of time putting things back together.
Everyone's Tri-Specced (Except Druids and Demon Hunters, for Obvious Reasons:)
Class Trainers have become a fully vestigial part of the game. You can now change specs at any time you're outside of combat, and it will simply treat all three (or two for Demon Hunters and four for Druids) of your specs as you would treat dual-specs, with saved action bar layouts and talent choices.
Somewhat More Commitment to Talents:
Talents can now only be changed while in a "rested" area like a friendly city or an inn. So you'll need to choose a good loadout of talents for the content you're intending to play, and you won't be able to swap them out between every fight (unless you want to really tick off your fellow party/raid members as they wait for you to hearth and summon you back.)
New Transmog System and Appearances Collection:
You will now permanently collect the appearances of any gear that is soulbound to you, as long as it's appropriate to your class (Warriors can't collect cloth appearances, Priests can't collect gun appearances, etc.) You'll also automatically get the appearances of every quest reward from every quest you've ever done.
You can also get Weapon Enchant Illusions, which come from multiple sources - some as boss drops, some from reputation vendors, and many come from items that Enchanters can create called Tomes of Illusion. These illusions will be counted among your Appearance collection and can be applied to weapons by a transmogrifier NPC.
You can now choose to hide helmets, cloaks, and shoulder armor using the transmog NPC.
You can put together and save transmog outfits with the transmog NPC, allowing you to easily switch between sets you like.
You can also now choose to transmog your gear a certain way only for a specific spec, so your Rogue can have a shadowy assassin look for her Subtlety spec while going for a more flamboyant pirate look when she switches to Outlaw.
Spirit, Bonus Armor, and Multistrike are gone and will be converted to other stats when the patch goes through. Likewise, in the future, Rings and Necklaces will no longer have Strength, Agility, or Intellect on them, while Cloaks will have all three. Thus, going forward the only piece of gear you're going to have to swap out when you switch specs will be your weapon (especially when Legion itself goes live and we all have spec-specific artifact weapons. For now, if you want to switch from Fury to Arms you can just unequip your off-hand weapon.)
Broken Shore Event:
Likely the first major thing to be live, the Broken Shore event is a quest chain that has you assaulting the Broken Shore, which is where the Tomb of Sargeras and the main base of Legion operations in Azeroth are. Following this event is a questline that sets up some of the future story of Legion and awards some 695 gear, including a weapon.
Doomsayers and Dreadlords in the Capitals:
You'll find doomsday cultists distributing literature in Stormwind and Orgrimmar, and occasionally random players will be affected by Dark Whispers. This causes them to briefly side with the Legion. You can opt out of this by right-clicking the buff, but if you don't, you can use various sneaky abilities to subvert your allies and convert them. If you find yourself caught, you can then transform into a massive Dreadlord, which gives you new abilities to use against the pathetic mortals that stand against you.
Legion Invasions - Sometime Later:
Some time after the patch has been released, demonic invasions will begin to hit Westfall, Dun Morogh, Hillsbrad Foothills, Tanaris, Northern Barrens, and Azshara. These are massive events where a huge contingent of demons will assault the biggest population center (in Dun Morogh they go for Kharanos and in Azshara they assault the northern gate of Orgrimmar.) These invasions go in four stages, with stage three seeing demons flood the entire zone. Completing these invasions gives you a currency called Nethershards, which can be traded to Illidari vendors for gear and a battle pet, and you'll also get loot boxes with item level 700 armor and a chance to get a 700 weapon or an item to increase the item level of one such weapon, up to a max of 725 (the upgrade item can also be purchased from the Illidari.)
Demon Hunters - Sometime Later, Probably August 17th:
Players who have pre-purchased Legion will be able to create their Demon Hunter characters at some point later in the patch. Blizzard has said that they will be available August 17th at the latest, which is about two weeks before the expansion launches.
Demon Hunters are WoW's second Hero Class. They are a melee class that can Tank or DPS. Demon Hunters dual-wield their own special weapon-type called Warglaives. They use fel magic to become partially demonic themselves in order to fight against the demons of the Burning Legion. Only Blood Elves and Night Elves can become Demon Hunters, but they get some unique character customization options, including tattoos, horns, blindfolds, and potentially scales. Demon Hunters have their own voice-over emotes as well.
Demon Hunters begin at level 98 in their own class starting experience. When they finish their opening quest chain they should be level 100, and thus ready to head to the Broken Isles along with the other heroes of Azeroth.
And Then Legion:
Legion launches on August 30th. I think that we're all chomping at the bit to get out of our garrisons and return to Azeroth. This is how all that begins.