In the Forgotten Realms, there were many cataclysms, like the Flight of Dragons (Dragons went crazy, and attacked everything in their path), the Fall of Netheril (and its floating cities), The War of the Phaerimm that created The Desert of Anauroch (which ties into the Fall of Netheril), and further south, the Kingdoms of Unther. Mulhorand and Thay are remnants of the breakup of the Imaskari Empire, which was started by Refugees from another world. It was eventually overthrown by the race they brought as slaves from their world.
And then there is the DragonLance Universe. It has a cataclysm in its history as well. Literally. Since at the Cataclysm, the Gods stopped helping humans on Krynn. They get to come back later, at the Current Apocalypse, the War of the Lance- but other things happen as well. And then there is the fall of the Ogres, once the most beautiful of races, now ugly and debased (they used to be known as the Irda).
A very interesting article, but I also think you need to contrast an Apocalypse (the ending to a whole world, as it is commonly taken), to the fall of a ancient civilization- which need not be an actual apocalypse. I think Cataclysm suits better here. To the people who live in the country or culture that is falling, it may seem like an Apocalypse, but it isn't.