Sinn left out key information about why this is even halfway credible.
Two days ago, a Chinese poster 见崎_鸣 posted on tieba (Chinese reddit) that a new shaman skin was going to be released, and that it would be Morgl.
近期会有傻馒新皮肤,大家来猜一猜是哪个人物 还有获取方式
There will be a new Shaman skin soon, anybody wants to guess who?
and how do you think you can obtain it?
麻蛋 不放干货没人看了 摩戈尔 招募。 粑粑闪了
Fuck, nobody wants to guess if you don't reveal anything. It's Morgl. Bye.
It didn't get much attention then, but naturally a lot of people bumped the post up today.
From there, he said that the upcoming adventure would be a WoW raid that has 3 Chinese characters.
下一个冒险是三个字的团队副本
The next adventure is a raid with 3 characters
Here are all the thus-far released WoW raids that have 3 Chinese characters (some of the ones Sinn posted are incorrect, the full names are not 3 characters):
Karazhan 卡拉赞
Ulduaar 奥度尔
Terrace of Endless Spring 永春台
Highmaul 悬槌堡
Karazhan is, of course, the speculated front runner currently for various reasons.