Whoo boy. If you were worried about not getting WoW news at Blizzcon this year, worry no more because, well, holy crap.
This patch will do things like class balance (non-Survival Hunters are getting traps back, for one thing.)
We'll also see the return of the Brawler's Guild, adding new bosses that can be fought by multiple players while they wait in their Brawl queue.
7.1.5 will also add Mists of Pandaria Timewalking dungeons. We won't see Warlords ones yet, as they plan on always giving you an expansion-long break from any set of dungeons. So we'll likely get those in the expansion after Legion.
New Artifact Knowledge catch up mechanics will be put in place.
We'll also get a number of micro-holidays like Ahn'Qiraj Remembrance Day. These won't have huge rewards that you'll feel bad on missing, but it'll spice things up.
7.2: Tomb of Sargeras
This will add Tomb of Sargeras as a 9-boss raid, with Kil'jaeden as the final boss.
Order hall campaigns will continue, and the reward will be a class-specific mount for every class.
Making it to the Tomb will involve a campaign similar to Quel'danas or Isle of Thunder, and you'll be able to choose different buildings that affect the story and give different benefits in the zone.
Legion Assaults, similar to the ones we experienced in the pre-launch event, will start hitting the various zones of the Broken Isles. This will put World Quests on pause, but will have its own rewards. At the end you'll be able to queue for a 3-player scenario (like Mists ones - role agnostic) where you take to the skies and fight aboard legion attack ships.
Oh, and speaking of the skies: Broken Pathfinder Part Two will be available, which will be account-wide and allow flight on the Broken Isles. No dungeons required - just world content (one I'd expect is exalted with all the factions, given that part one required revered.)
Artifacts will get new traits, and you'll be able to put a 4th point in all your 3-point traits. Also the cap on Artifact Knowledge will go up.
New relics that modify multiple traits will also arrive.
There will be new artifact appearances that involve challenging spec quests similar to Anathema/Benediction or the Warlock Green Fire chain.
Court of Stars, Arcway, and Karazhan (the latter broken into two halves) will have queueable heroic modes.
Additionally, a new dungeon: Cathedral of Eternal Night, will be a 4-boss dungeon with normal, heroic, and mythic + difficulties (I'd assume also a regular mythic mode.)
PVP Brawls, similar to those in Hearthstone and Heroes of the Storm, will be available in WoW.
We're going to FREAKING ARGUS.