So due to changes in guild and server I will be maining prot in WoD. Got into the beta a couple days ago and started leveling as prot just to get a feel for the changes. It is 100% viable. you wont 1-2 shot stuff like you would as arms, but I have been 2-3 shotting most stuff and I am able to solo elites and rare mobs very easy.
Don't have rights to link the simulation, but we're looking at ~94% uptime on shield block with 4 set. That combined with the fact that we'll be approaching crit block cap in mythic gear... the only melee hits we'll be taking will be for 22% of the full hit. Definitely overpowered, and certainly does not reward intelligent decision making.