User blog comment:Sky-Dragoon-Twilight/Weisslogia and Skiadrum, Alive or Dead?/@comment-25849146-20141211044435/@comment-9595671-20141211195835

We likely won't know for sure, though I recall Igneel mentioned in the GMG right during the 4 Dragon Slayer fight that they want humans to surpass dragons. That has a role most likely as well.