Well I've quit WoW some 4 years ago but I must say I honestly envy the spare time some people have that they put their whole effort into such a thing. I wish him good luck but I don't think it's doable. At least not with a hardcore character and from scratch.
Edit: From his stream channel: "My focus will entirely be on Diablo III hardcore. Normal just isn't enough of a challenge for me. However I will start out by playing through the game once or twice on Normal just to learn the game so I will be able to adapt to every situation and never die again! At least that's what I'm hoping for ;)"