Considering what the Calamities really are in the game's lore, and given that Endwalker is winding up that original storyline, and thus SE will be taking the story in a new direction after that, using a Calamity as an excuse to wind up the game like what happened in 1.0, simply will not occur again
(Calamities are how the Ascians 'rejoin' a Shard of Hydaelyn with the Source as part of their plan to recreate the original world they inhabited which Hydaelyn split in order to break Zodiark's power.
EW's 'end times' story almost definetely will not be reflected in the greater game world other than some graphical imbellishment and battles that will be exclusively instanced, as the game world has to be consistant for new players after all. You're simply not going to see a repeat of the 'Seventh Umbral Era' events 1.0 had in it's last months as there is no reason to do so.
You have to remember that the Seventh Calamity was specifically set up gameplay wise to not only send the original game off with a bang, it was also meant to explain the changed zone maps between 1.0 and ARR. ARR has no reason to be replaced in the same way it replaced 1.0 given it's immense and continuing success.