Breath of the Wild: The King of the Merge

The history of the of the Royal Family of Hyrule is also the history of the Calamity Ganon, a primal evil that has endured over the ages...
- Impa

I think, you are now ready, ready to hear what happened 100 years ago...
- The King of Hyrule

The Triforce. The sacred triangles left behind by the Goddesses, after they created the world of Hyrule, will grant any wish to whoever touches it. However, if someone with an unbalanced heart touches it, it will split into three pieces. This is the Legend of the Hero of Time. After the evil thief Ganondorf entered the Sacred Realm and tried to conquer the world using the Triforce, it split and a battle over Hyrule unfolded. However, not only the Triforce was left split after this battle, but time itself.

The world of Hyrule kept existing in three different times, but each of them was haunted by the calamity that is Ganon. Because of this one Hyrule was reigned by darkness, another was flooded by the Goddesses and in the third a constant battle over the Triforce occurred over the ages. But the battles were ultimately won and the Triforce left in the possession of the Royal Family of Hyrule, where they could use its power to do good. The Sheikah, who protected the Royal Family since the early times, even were able to create new, magical technology to bring Hyrule to prosperity.

One king, however, learned that his prosperous kingdom is in fact just one piece of a broken world, broken in the veins of time ever since the Hero of Time fought Ganondorf. With all of them plagued by evil, the king decided to use the Triforce to reunite the worlds to form one new peaceful kingdom, guarded by the technology of the Sheikah. But this had its price. Not only were the worlds of Hyrule united into a gigantic new land, but also the Calamity of Ganon, forming a massive evil of unseen power. The Sheikah were able to banish this evil into Hyrule Castle with an army of Guardians made from their magical technology. But the new world of Hyrule ever since is at unrest.

...

This or something similar I could imagine as the backstory of Breath of the Wild, to put some more meat into my timeline merge theory from June. It would be quite the epic fan service to use Ocarina of Time and the Legends about the Hero of Time as the starting point, where the timeline split is in coherence with the split of the Triforce. The nice twist about this approach is that it was ultimately the king's fault that Calamity Ganon got created and now haunts Hyrule Castle.

There is even a scene from the trailer, which supports this theory somewhat, where Zelda looks at Hyrule Castle in what's clearly a flashback and you can see a glowing light coming from it:

This might be the king making his wish...