Those new models look sick, will they ever be playable? blizzard kind of gave an answer, that making all the old amours fit the new models would be too "expensive", but they also implemented Pandaren which nullify that same statement because as we saw Pandaren can use all the old amours and they look crap on them, supper stretched chestplate, crap looking legs, etc. As for the costs of making the new amours models for that many races being to "expensive", it's bullshit, players pay 15€ a month to play the game, they make more than enough money to do it, and the art team in wow is amazing.
edit - No idea why real life PC shit is showing up in the comments, but don't post about it I (like most people) don't give a fuck if you're fat or thin, it's a game, and this is about the possible player models not real life issues.