I can think of a couple affliction warlocks with poor coordination who do relatively well. You can always dual spec and try out whatever you like.
Just remember that nigh invulnerability belt = AGM and herbs is almost as OP at 59 as 19.
Ehhh, fire is pretty facerollable at 59. And they definitely come out behind frost with a good player at the helm.
Destro is crazy good "if played right."