Given the fact that we're getting updated Hero costumes through Golden Pursuits, as well as the fact that the upcoming Season 1 storyline is almost certainly about the Worm Cult, I think it's the perfect time for ZOS to release an updated Mannimarco "Hero" costume which closer-aligns with his armour in the famous Three Fates cinematic.
His current costume was made around the time of the game's initial release, back when the game was heavily constrained by technical limitations. That's no longer the case, and it's now possible to make a far more detailed costume along the lines of what Mannimarco wears in the cinematic. Given the story relevance, it would make sense to release during this period. The Golden Pursuit system also gives ZOS the perfect excuse to do it since those other cinematic costumes are getting high-res updated versions too.
The stars are aligning for an updated Mannimarco costume. Please ZOS, make it happen!