Personally I don't see them get cured in sense of returning to human life. But their torment can end by soul transfer into a functional body, which either is flesh crafted or maybe golemancy. If that option happens pretty sure they will stay with the Horde, even if they likely become less vile.
Edit: The short on the restoration of Nanathos shows there is possiblity of this, but takes to much. My guess if they can end up controlling Yogg-Saron this might become a feasable future of the forsaken.