Prepare to have your mind blown

[Zantetsuken]

The gravitational pull of the moon will deform the world itself, and pulling up the crystal tower and other things with it.
That's how i always looked at it.

Thats a plausible explanation for the map revisions.

Even little things like the Chained-down floating Aetheryte point would point to this.

Still, it can't be the full explaination as the main cities are going to be rebuilt, there will be trains, new towns, ruins and lots of other stuff that can't appear overnight.

Here are the options I see:

20+ years pass between Dalamud's impact and 2.0, Players 'wake up' in the future somehow
-or-
The 7th Umbral is actually an echo experience and players are really living in the 2.0 future.
-or-
Dalamud is sent back in time before it hits (Atomos?) and it alters the present day as a result.

In my opinion, the 3rd option may end up being the most likely. Any alternative would require the replacement of all NPCs quests and cutscenes in the game - something a frantically busy dev team would want to avoid.