It's much more than a thread, m'boy!
It also must be mentioned that Spirit Track's train represents a logical upgrade in the Zelda universe. The game is a symbol for the everlasting struggle between good and evil, and thus, Link and Ganon will continue fighting for all of eternity. A game featuring more advanced technology than past games is a good step forward.
It is this accurate reading into the series that has inspired me to create so many spin-off stories and projects to differ from the formula. I like to look at it as though Link and Ganon are essentially one in the same, and like Zelda said about Hyrule and the Twilight Realm: two sides to the same coin; they cannot exist without one another. However, this might be stretched further to the number three, as the three pieces of the Triforce cannot exist without one another, and hence, Link, Ganon
and Zelda exist only because the others do. They balance the world. One opposes the land, the other two oppose him. When both exist, they will always triumph.
However, screwing around with such infinities such as "time" would warrant undesirable results, as seen in the prelude to Wind Waker. This further questions what is right, what is supposed to happen, and what is not. Everything that has happened... was it supposed to happen? What if no one wanted it to happen. Was it supposed to? Well the fact is, it happened, so I would say that it was supposed to happen, not many how many forces in the universe oppose it. Even if time is warped and history altered. What happened at one point was supposed to happen, and the alteration too, was supposed to happen.
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EDIT: I wanted to end this with something climactic, but I had nothing until now. What is truly beautiful about The Legend of Zelda is that the entire scheme of it all is based not on the number two - which so many things in our real world are - but rather one
more than two; three. The simple number
3 has become so much, as it pervades the very fabrics of which Hyrule is woven. The Triforce is simply an archetype - a triangle, built of three triangles. What is significant in the triangle is that it is the most basic shape when connecting straight lines. One is simply a line. Two defines every angle imaginable, but three. Three, now you have a tangible, visual shape. In a certain light, it is
the most basic geometric shape. Yet, this whole, beautiful, magical world is crafted around the idea of the triangle, and all that it entails. But the Triforce itself says so much more. Bringing three triangles together to form
one triangle is as powerful as the number 11. So much of our world is based around the number and idea of ten; 10. But, you add one more;
just one more number to ten, and you surpass it. Ten is composed of ten whole numbers, but that one more beats it. That's all it requires; a simply push over the edge. The Triforce, I feel, is that much more important than a single triangle. On the surface, it is just two more triangles than the basic
one triangle, but more so, a new triangle could not be formed without those two more. Not just one more, but two more.
So in a nutshell, Shigeru Miyamoto is a sheer genius for developing this immortal symbol.