I love a good theory, not sure I know enough about this one, but I might chip in just for lulz
What I like about this theory, hard as it is to prove or disprove, is what it would mean for the Zelda universe if it were true.
[SIZE=13px][COLOR=rgb(241, 241, 241)]Note: This theorizing will be done from an in-universe point of view, meaning that I'm looking at this theory as if Hyrule and Lorule are real. This is extremely important, as doing it any other way would open up the argument that games that were created before A Link Between Worlds would not be able to reference Lorule because it was not created yet.[/COLOR][/SIZE]
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It's an interesting theory, and it would make sense, but I don't think it was Nintendo's intention. Skyward Sword was made way before A Link Between Worlds after all, and I'm not sure this is the kind of thing they'd be planning out so far in advance. Unless they came up with Link Between Worlds based on the story in Skyward Sword, somehow?
Well, that's not strictly in-universe, but it could be that some people at Nintendo thought 'Demise is from another world? That sounds like something cool to go into, let's make a game which starts to expand on his background'. As the chronology and theories surrounding Zelda get deeper, I think Nintendo take it more and more seriously to maintain cohesion and continuety ( consistent universe = happy and inspired fans = $$$ ). I do think it's interesting to take out-of-universe arguments into account, because it opens up conjecture as to whether Nintendo's future moves will prove or disprove a theory. On the flipside though, if a theory holds up for in-universe reasons, but couldn't have been intentional for out-of-universe reasons, Nintendo could always make it cannon in their future material. For example, they could catch wind of this theory about Demise being from Lorule and say 'oh that's cool, ok we'll make that reality and confirm it in our next game.'
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and clear counterparts to Link, Zelda, and Ganondorf (Ravio, Hilda, and Yugu).
If Demise IS from Lorule, he must have cast his hate curse in Lorule previously, otherwise, why would there be a Ganondorf? What's more, we could predict when it happened by working backwards. Demise assumedly came to Hyrule shortly after the destruction of their Triforce. It seems that the sacred realm in Lorule was well explored and exploited, so it stands to reason that Demise could already know of the fissure before the destruction of the Triforce, or he would have found it soon afterwards as he scours the Sacred Realm for traces/fragments of the destroyed Triforce. Also, the destruction of the Triforce would mark (roughly) the time that Demise's powers had reached their height and he would be able to inflict such a curse.[/COLOR][/SIZE]
Now, I've never played A Link Between Worlds, so I'm going purely on the information you posted. It's not yet on the official timeline to my knowledge, so is there any information about where on the Zelda chronology A Link Between Worlds is meant to take place, and how recent this destruction of the Triforce happened? Because that could destroy the theory - it has to be possible for the Triforce to be destroyed before Demise comes to Hyrule, which in itself is a long time before the events of SS.
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It has the inverted Triforce on it. It's a backless assumption because we just don't know, although it explains why Lorule is missing a Master Sword equivalent — Demise took it to Hyrule and was killed.
Well, the picture you posted of what I assume is Lorule's Triforce is itself inverted, so that's a sort of evidence. I'm unsure if there's meant to be a link between the master sword(s) and the Triforce(s), but it's worth bearing in mind Lorule's Triforce is destroyed., if that means anything to anyone.
My favourite aspect of this theory, though, is its implications. It would make a huge difference to the nature of the Zelda universe.
CASE 1: Theory Is False
The creation of the world by the three goddesses is the ultimate beginning of Hyrule, they are the source of all things. One can imagine some kind of theory about how evil and Demise came to be - he is their balancing opposite, or came from some shadow that Farore didn't reach, or something. Anyway, the world has a beginning and an origin.
CASE 2: Theory Is True
Demise comes from off-world, thus evil in Hyrule originates off-world. But even in Lorule, Demise can't have come from nowhere - evil must have existed there too, he must have had an origin. Do they have their own version of Demise (a proto-demise), which then cursed everyone and so Demise is his reincaranation, in the same way the Ganondorf is an incarnation of Demise? Now you could point to the existance of a Ganondorf equivalent in Lorule to disprove this, but wait a moment. Incarnations of incarnations are already a theme in Zelda. Consider Zelda herself - as the timeline progresses, she grows more and more distant from her origins. First she is a Goddess, then she is a mortal Princess, the reincarnation of a Goddess, then she is the pirate Tetra, who is a reincarnation of a Princess, who is the reincarnation of a Goddess. Could the same pattern hole true for demise - Lorule had a proto-demise, who is reincanated as Demise, who is reincarnated as Ganondorfs in Lorule and Hyrule? And as the series progresses, Ganondorf's power grows, to the point that he is referred to as a God in Twilight Princess. One day, will he aquire Demise's level of power again? Will Hyrule's Triforce have to be destroyed, and/or will he invade another world and inflict a curse of his own? Is everything an endless cycle? This is all purely conjecture, but it's not completely baseless, it's derived from observable patterns: people like Zelda and Ganondorf grow more distant from their origins as the series progresses, Ganondorf gains power over time, things in different worlds affect each other. I'd like to say it even throws into question the goddesses themselves, and if they are the ultimate form of Zelda, Ganon and Link at the very end of another world's history... but maybe that's taking it too far. I think, overall, it's just a cool idea.[/COLOR][/SIZE]