E3 2021 finally provided Nintendo fans with more footage for the both Link and Hyrule have changed in the time between the two games. This, combined with a new ability - what appears to be an evolution on the Stasis Sheikah Slate power - is lending new credence to a theory that the Breath of the Wild sequel is going to take place in an era prior to the first game.
Time travel is not an unfamiliar concept to The Legend of Zelda. In Ocarina of Time, both the Master Sword and the Ocarina of Time itself had time manipulation capabilities, with the entirety of its sequel, Majora's Mask, revolving around a time loop. Skyward Sword used temporal stones to great effect in one of the Legend of Zelda's more creative dungeons, and a few other entries in the series have used similar game mechanics.
The rather convincing theory for the Breath of the Wild sequel heavily involving time travel is explained in a video by time travel theory is borne from the lack of ancient Sheikah structures (Sheikah Towers, Ancient Shrines, etc.) present in the first trailer's look at a floating Hyrule Castle. Additionally, Zelda and Link appear to be riding creatures not found in BOTW, presumably because they were driven to extinction by one of the Great Calamities.
BOTW 2's New Trailer Has Plenty of Time Travel Evidence
The Stasis ability from the Sheikah Slate in Breath of the Wild only let Link freeze objects in place for a short time, making them glow a bright yellow. BOTW 2's gameplay trailer shows Link using a similar ability (this time with a new arm instead of the Slate) but with the power to rewind time for the affected object - the trailer's example being a spiked ball rolling back up a hill. There is also a short shot of a pool of water reforming into the droplet that fell to the ground. These sequences are important to the time travel theory because it shows that significant time manipulation - specifically time being reversed - is possible, but there are also other details that the theory.
A major one comes from the new trailer's shot of floating Hyrule Castle. Just like in the first trailer, it appears to be a mostly intact castle, with no Sheikah structures in the surrounding area. More importantly, however, is the existence of un-destroyed buildings in the foreground, implying this scene takes place before one of the Great Calamities. Perhaps Zelda and Link went back in time either 100 or 10,000 years to stop the Calamities from ever happening.
The final bow that wraps the time travel theory into a nice package is the ostensible presence of 's theme song played backwards in the new trailer (it's since been noted that it may not be the actual theme, but is still music played in reverse). It seems odd to use music in reverse, if it weren't symbolic of events being undone. Moving into a different timeline would also help explain Link's new look in the Breath of the Wild sequel, and give Nintendo plenty of opportunities to switch up the first game's map.