'Twas brillig, and the slithy toves did gyre and gimble in the wabe

If you're trying to fit my theory into the game, it won't work. The best you can do is fit the game into the theory, which is how I came up with it in the first place. Because OoT's a game, you can do things in it that you can't do in the real world (like travel through time). But if you take the basic idea and structure of the story, you can create around it a plausible enough tale.

Seven years later, he returns to Hyrule in the year 2007 and... now what? If I've got it right so far, at this point there's two Links: the Link who grew up the slow way (and has a watch saying 2007), and the Link who travelled through time (and has a watch saying 2000). This doesn't make sense to me, though I may have misunderstood your post.

I see what you're saying, and this idea presents an excellent point, but it also depends on 2000!Link successfully travelling through time. For the sake of my theory, he can't do that, just as you can't do that in the real world (sorry, I should have been more clear the first time around). Say, when he gets to the Sword for the first time and attempts to pull it, that somehow opens the pathway to the Sacred Realm -- allowing Ganondorf to get in -- but the Sword does not accept him. From a third-person view, the blue light comes and goes, and Link heads back to Hyrule Castle. He meets Zelda again, blah, blah, blah. 2000!Link will eventually return to Hyrule to claim the Master Sword, and his watch will say 2007.

As for Zelda sending him back, it's magic-based, so anyone can say how the magic works, since it doesn't actually exist. Perhaps when Link is sent back, Zelda can send him back to the EXACT point he touched the Master Sword so that the two Links, existing in the same place at the same time, are actually one and the same. Perhaps she doesn't do it correctly and Link's shunted to another dimension, or he just fizzles away (since, remember, you can't actually travel through time!). I don't know. The point is, at any given point in time, there is only one Link.

I don't understand how the other single timeline works. How can you change viewpoints a la Wind Waker if past! and future!Link don't exist at the same time?

I think the timeline that makes the most sense to me is a single timeline one where the future never happened.

I thought that was the basis for the split timeline? That when Link is sent back through time, it creates a split where a) Ganon(dorf) was defeated -- the adult timeline; and b) nothing happens to Hyrule because Ganondorf never got started -- the child timeline. Personally, I don't see how that works, because changing the future does not affect what happened in the past. Something I do today will not change what happened ten years ago, but what happened ten years ago probably very much affected the person I am now.

... the Hyrule of 2007 is much the same as the Hyrule of 2000. The only people who know what happened are you, and possibly that dratted owl

How can he possibly remember things that never happened, especially if he never travelled through time?

I'm sorry if I misunderstood any bit of your post; this really is very confusing.