There's a point in the music where you can clearly hear 'help us'. Some dude deciphered it all on Reddit and he actually wasn't reaching. Here is the post:
"I've figured it all out. This trailer proves BotW to be a part of the Child Timeline, featuring OoT, TP, and Four Swords Adventures. You can read that timeline here(just control+F search for Child Timeline).
First off, it is important to note that spooky white hand is a good guy. This is evidenced by it catching Link and Link being able to harness its power. Moreover, if you play the trailer's music backwards (hear me out) you can hear a whispering voice saying "Help us... Please." at the 0:45ish mark, specifically a woman's whisper between 0:47 and 0:49. (GOD I LOVE NINTENDO!) What's crazier is that if you take the exact time that part is played in the trailer, 0:35, you see Zelda get startled and notice the glowing arm holding Ganon down. It is legit crying for help. It's timed perfectly. This is not coincidence.
The Child Timeline starts after Ocarina of Time. Link saves the day, becomes a child, warns the King of Ganon's evil. Moving into Twilight Princess territory, the story says that once Ganondorf's intentions were made known, he was to be executed by the Sages. They impaled him IN THE STOMACH with the Sword of the Six Sages. He didn't die because of the Triforce in him, so they banished him to the Twilight Realm. TP story commenses and we are reminded of the wound in his stomach during the Ganon Pig fight when you turn him over and strike at the wound ON HIS STOMACH. Well, if there were a spiritual weakness in Ganon (mind you this is the last evidenced time we have of Ganon being in Human Form, only under assumption he did during BotW) what better place to hold Ganon down, than by the stomach. (Edit: I'm sorry I said "in the stomach" >.< Looks like the sternum, but either way, the location seems to line up )
Next piece of evidence is a smaller detail. In the chambers of the cave Link explores, there are cave markings. During the Four Swords Adventures, Ganon is reincarnated from his TP death. As he and his band of thieves gets kicked out of the Gerudo Tribe, he STEALS THE TRIDENT from the Desert Pyramid. He uses this trident to hunt down the knights of Hyrule and transform them into demons. He then is sealed away. We still don't know much about BotW Ganon, but Four Swords Adventures Ganon is described: "Ganon...This beast was once of the Gerudo...Once human. He was called Ganondorf! King of Darkness, ancient demon reborn. The wielder of the trident!!" — Princess Zelda (Four Swords Adventures). The cave drawings depict a pretty scary dude on a horse wielding a trident. There are other games where he uses a trident, but this timeline is one where he used it as a Human before becoming a beast. Although he does use a trident in Downfall Timeline, Ganon does lose his memory between using it and BotW.
Ganon was defeated milennia before BotW by the Divine beasts so Ganon's reincarnation was of Beast Ganon so he could send his phantoms to take over the Divine Beasts. We know that Ganon attempted to return to a human form in BotW, but the compendium states: "it attempted to regenerate a physical form after Link awoke but was forced to confront him in an incomplete state." Zelda never let him return to a human form before destroying him. I imagine something in this inspires Ganon to find his 1000 year old self who originally attempted to capture Hyrule. Ganon is known for switching between his two forms for another shot at killing Link, but never got the human chance in BotW.
Where Ganon stays in the trailer is a prison. Spooky hand is good. In Skyward Sword you gain an idea of how Ganon (or Demise, Ganon's earliest form) would be Imprisoned, in a spooky red/green runic circle with oozing evil magic.
My last interesting point here, in Skyward Sword, Demise is finally contained by dropping the Goddess Statue and a portion of Skyloft onto his prison. I find it completely rational that after the inhabitants of Skyloft came to land, they would want to build Hyrule on a sacred location, and this spot feels the best. I wager that this whole scene occurs in those tunnels beneath Hyrule where the Ancient Sheikah well versed in ancient texts followed suit and imprisoned Ganon's body. Well if a falling city can imprison an ancient evil, then what would a rising city mean?
Hype intensified. Let me know what I got right and what I got wrong!
EDIT: I'm loving the feedback here! Great discussions and interesting points for and against this. My goal was to harbor this discussion and this has been great. Of all the comments I've read, there has been one that has bothered me a little bit, so I'd like to address it. The comment generally goes, hasn't Nintendo said BotW belongs to none of the timelines specifically. Here is one comment the director's gave about the game:
Eiji Aonuma, series producer: “Well of course it’s at the very end. But, I get what you’re asking, it’s which timeline is it the end of?”
Hidemaro Fujibayashi, director: “That’s… up to the player’s imagination, isn’t it?”
On another occassion, Eiji Aonuma says: "I wouldn't say that it obviously fits into any one part of the timeline, but if you play the game, you'll be able to work out where it fits.... I don't want to say anything more as I'd like players to work it out for themselves, to play the game and see what they think."
I understand the comments saying, "You have thought more about this than Nintendo has," and they might be right. But that's okay. They want the player to explore and build the world themselves. THAT IS THEIR VISION.
Realistically, they can't bog themselves down by a timeline because it limits their potential in creativity. If they said it was X timeline, maybe they couldn't give us the wonder that was BotW, or may be BotW 2. However, they care enough to hint at past games' lore. I feel they are giving us as many tools as they can to reference Zelda lore while stopping short enough to keep their creative liberties that a business requires. Heck, maybe after BotW 2, they can break this previous convention anyways.
Hopefully I've provided enough interesting points of evidence to help you to decide which timeline it falls under and follow Fujibayashi's mindset, to leave it up to "the player's imagination."
Don't get too worked up, we're just having fun