Hello, I work in animation and recently came into contact with someone who is doing 3D modeling for Blizz right now. Basically when Blizzard is putting an expansion together, they sign short contracts with artists to get the bulk of the work done. The contracts are usually up before the expansion launches and most artists aren't offered permanent jobs on the actual art team. In other words I'm getting my information from the outer circle, not the inner circle.
Pre-patch event involves Azshara attempting to capture Quel'Thalas and Darnassus due to both their vulnerability and history. Naga invasions will begin on Darkshore, Azshara, Teldrassil, Eversong Woods and the Isle of Quel'Danas. These invasions are meant to feel severe to "hook" players, so there will be a lot of bloodshed and dead fodder. New recurring naga characters will be introduced, and rewards include new underwater mounts.
Undermine
The Horde's city is Steampunk themed with a dark color palette. Jokingly described as "Ironforge, but with water." Has idustrial features like Gnomeregan's flourescent lighting, elevators and alarm system. Where Gnomeregan prized innovation, Undermine revolves around money. The locals are mostly pickpockets and aspiring tycoons. Quests begin with Undermine goblins deceiving and stealing from players. Players earn their respect by becoming street-savvy and making money.
Kul Tiras
The Alliance's capital is the opposite of the Undermine. Kul Tiras's color palette is summery, with splashes of soft blues and dark greens. Players arrive at the
beginning of a bountiful harvest, and the natives are resentful about hosting them. The island nation is thriving, and residents worry the players will bring trouble like they did to Pandaria. Players earn their respect through feats of strength against the naga and Horde.
Leveling zones are disconnected like in Cataclysm, although this is meant to be "remedied" by scaling technology. When players get to choose their next zone rather than having it determined for them, they enjoy the exploration more. Players will revisit both 1K Needles and Stranglethorn Vale while leveling, although I don't know in what capacity this will be. Players will also visit many new zones, including:
Kezan - somewhere between Un'Goro Crater and the Echo Isles. You can see the beach from most anywhere in the zone, and the setting is very tropical. Huge deadly predators roam the island, and Kezan natives are reluctant to teach players how to survive here.
Plunder Isle - still under ideation, no color palette or general aesthetic locked in yet. Direction involves players fighting the Bloodsail Buccaneers and invading
Bloodsail Hold, it's undecided whether this conflict should be resolved while leveling or through max level content.
Tel'Abim - though a small zone, uses two entirely separate palettes. Tel'Abim looks like any other island, and houses one of the expansion's few friendly races (unclear who). Quests here begin with physical labor to help the locals, but players eventually discover "dark forces" infesting the island (my personal expectation is old god stuff). The situation escalates until Tel'Abim is warped and shifts into its second color palette, which is mostly dark blues, dark greens and bright purples.
The Maelstrom - a group of small islands near the storm and the frontline of the war against the naga. The assails players with jarring visual effects and debuffs, while the naga draw power from it. Grays are heavily used, from the rocky terrain to the stormy weather. Like the prepatch event, fighting the naga here feels very intense.
Out of everything here I'm most excited about the new cities. I'm also worried about the fate of Plunder Isle, hoping it doesn't go unfinished like Azjol-Nerub or The Abyssal Maw.