I am on board with you, this is amazing news, and I'm excited to play though the destruction of the old XIV and then come into the world of the new XIV. It's super exciting stuff.
I know there were those who where crying to shut down the servers, but in essence this is what they have done. They are keeping old XIV alive and re-building it from the ground up and we get to keep our characters. This will help with lore issues, story going forward, it's a brand new world, day, game... And we get to play how it happens, how often does that happen, it's our very own catliclism(sp?) so to say. It's a story that is one time though.
Also, on the road map, they have a section that says "phasing system" so it sounds like as we play the game things will change.

Sweet!