That SH will accompany the main Shadowspawn army in their battle at TG. We already see him in armor in CoT and he says that he has to cut the bond to SG. Maybe SH will even show the ability to link with all other Myrddraal, who can themselves link with the Trollocs, to create a "super fist", so to speak. This could also be used as a plot device to explain why most of the Shadowspawn will die, when Rand defeats the DO, since SH will presumably lose his powers & die, which might have a killing effect on all Shadowspawn linked with him.