Yeah, everyone has a good idea of
how will happen, but there is more beyond that.
I think the question is: How are they going to explain not only the geographical changes but the the sudden appearance of certain ancient ruins, townships, and other large
constructed features in the landscape?
Those things certainly can't appear overnight as a result the catastrophe in question. So what are the options?
I'll try expanding on the OP's options in the title (before he/she went crazy with FF7 tie-ins), as well as adding my own ideas:
- Cataclysm occurs and players wake up 300~1000 years later (perhaps Atomos sends us there?)... All current NPCs are gone, the cities are different and a new story begins.
- (variation on #1) The entire 7th Umbral Era experience was a result of the Echo. Players return the the 'present time' (2.0 era) and begin a new storyline in a new world with new NPCs etc...
- Cataclysm is triggered but occurs in the past and splits the timeline creating a parallel universe. Players awake from it to realize that the history of the world has been altered. Geography has changed, and current NPCs remain with no memory of what happened.
- Cataclysm seals off current areas of the world and opens others (think the differences in the WotG zones in FFXI). Cities change slightly but not much. This may be accompanied by a 5~10 year jump forward in time (player in a coma?) Current NPCs remain and the story progresses.
We've been told that all the maps are going to be rebuilt. This includes the main cities as well, but to what extent, we don't know. If there is a full rebuild, it would lend itself better to options 1, 2 and 3. If the team is trying to keep the cities as they are for the most part, then options 3 or 4 are more likely.