Nice article.
I'm not too sure how they will tie it in with the rest of the series, but I don't really think it needs to. I find it pretty obvious that t's connected with the dark world, which only really appears in two games. I think it is going to end up being the force that creates, or protects the Dark World, since the Triforce does that for the Light world.
I would like to point out that the Dark World, in ALTTP anyway, is a manipulated version of the Sacred Realm, in which the Triforce rests. This means that the triforce would need to be present within this world, but it would also be manipulated by dark forces.
I'm glad you mentioned Demise in that, since he very likely represents the devil, in the same way the Goddess Hylia represents God. Hylia sent the three Golden goddesses to protect the realm, and in doing so they created the Triforce. The Dark Triforce seems to be a sort of opposing force to the normal Triforce, similar to Demise and Hylia. I have mentioned in several posts at ZD how I am very eager to see the return of Demise, and this is the perfect opportunity.
Remember at the end of ALttP, the text says that the Master Sword sleeps forever. With Ganon presumably dead, who is going to be there to recreate the Dark World? Well, the only person I can think of is the person who holds the only connection available to the Dark Triforce, who just happens to be sealed inside the sleeping sword. He's not dead, so why can't he return? With nobody commanding the Master Sword, I imagine his seal would just get weaker and weaker, until he is finally able to escape. It's the only real possibility I can think of because of the lack of evidence we have that supports anything else.
About the Stone Tower Temple, I have to disagree. I'm fairly certain that the Triforce appearing there is a mere easter egg, because the Stone Tower Temple has no connection to Hyrule. The entire region of Termina is parallel to Hyrule, which means that they can't coexist, which therefore means that there can't be any connection to hyrule's Dark World. Good observation, though.