Blizzard have announced that the upcoming major patch, dubbed "Rise of Azshara" will arrive to WoW on June 25th!

They have released a new feature trailer for the patch:

Rise of Azshara Features Trailer – Arriving June 25!

Also there's a new deep dive with Ion Hazzikostas that explains the reward and design philosophies, gear reward scaling, gear and character progression, PvP gear crossover and class design coming with Patch 8.2.

Rise of Azshara Arrives June 25 and Dev Insights w/ Ion Hazzikostas

 Major highlights coming to 8.2 (from Wowhead)

• Heart of Azeroth Essence system
• Two outdoor zones - Nazjatar and Mechagon
• New Raid - Azshara's Eternal Palace, and Megadungeon - Operation: Mechagon
• Unlock flying via Pathfinder Part 2 in all zones including new ones
• Mount Equipment Slots
• Continuing the War Campaign
• Gnome and Tauren Heritage Armor
• Stratholme Battle Pet dungeon
• Dozens of pets, mounts, toys, new transmog, and other collectables
• New and upgraded items for all professions