Mastery nerf is likely
They could also nerf our damage reduction. Mastery can definitley work. if we gear mastery and reach 100%hp/healing received, and have 6mil hp while a warrior has 3mil... if a warrior takes 1mil damage we need to take 2mil to be even... plus we take double healing so its the same difficulty to heal back.
The problem is magic damage: they can't exactly make us take that much more magical damage... I guess it'll just end up being our strenght. They could nerf us to 0% magic DR and warriors stay at 25% magic DR, but if we have double the hp, a 1million magical hit at 6mil hp is 1/6th of our hp, while it's going to be 750k/3mil for warriors which is 1/4th of their HP.
I'm also pretty sure our damage and rage of the sleeper will get nerfed. Possibly boomkin affinity: it almost deals more damage than DPS.