I hate to be a buzz kill, but then what do you think will happen to the already implemented story missions? If the world is changed, how are they going to execute this correctly? Without giving too much away, the story missions progress though giving you signs that the age is coming, especially at the very end.

If the world is gutted due to the war in the Umbral age, it will not be cohesive when starting your character anew. In order to implement this change, they might need to have two separate maps. The continent in the astral age and the continent in the umbral age which would segregate the newer players from the more experienced and most progressed through the story.

This also could be a message that hints that the grand companies will be implemented very soon too and, although very possible.. don't get me wrong, not the redesign of the zones.

Who knows! The possibility of either or both are very exciting also, the thought of how exactly they are going to go about them.