I dont believe that they will be available for current raids. First we dont know if they even reach max level in the expansion. They only said that they will increase his level over the 5.x patches which could mean that he can be only 70 at the end. This makes sense if they dont want him in current content. If they dont balance him now why should they do that in the future? And if you have no balance then a Blue with all his skills would mess up current raids.