I have read that article by Hylian Dan, and I think it is very well done and an excellent interpretation of what the original Terminians might have thought and done with Majora's Mask. According to my recollection, I believe that the manual that came with the game stated that during the creation of Hyrule many other parallel worlds were created at the same time. This obviously applies to Termina.
There is also another article that I believe was originally published on ZU
that can be found here. This one by The Sheikah makes a possible link between the Fused Shadows in Twilight Princess and Majora's Mask.
It is definitely worth a read when you have a spare ten minutes, but it made me consider the possiblity that Termina fell sometime AFTER Link left. If indeed Termina fell afterwards, then that could mean that the people "gave the finger" to the Goddesses again as the article by Hylian Dan stated. If the Terminians "gave the finger" to the Goddesses, then They might have finally gotten fed up with the Terminians rebelliousness and banned them to the dimension that is called Twilight in TP.
But why would the Terminians do such a thing after they had been graciously saved by the Hero of Time and the Goddesses who sent him? Obviously, those kinds of things don't take place overnight, but consider the statistics of the people who started going to church immediately after 9/11 and then a year later after 9/11. People forgot what drove them into those churches in the first place, and everything went back to the normal hum-drum of life.
If the Terminians had made a habit beforehand of flipping off the Goddesses, then one single, catastrophic savior in the form of Link wouldn't change that habit. And, like any of the stories you read of any culture's mythical gods and goddesses, immortals seem to get fed up with people they created who don't respect them as they should.
In conclusion to this post that has turned out to be three times longer than I expected ( :rolleyes: ), I believe that the Terminians were *nearly* destroyed before Link arrived and were finally, completely destroyed after he left for their insubordinate behavior. Thoughts, anyone?