I still don't think that Breath of the Wild takes place at the end of every timeline. I'm firmly in the Child timeline camp. The only way I can see it being at the very end of a bunch of timelines is only if it is at the end of the Hero is Successful timelines (because I don't believe there are any mentions whatsoever to anything on the Downfall timeline, correct me if I'm wrong), and even then pretty much everything about the Adult timeline would have to have been forgotten and replaced with stuff from the Child timeline, such as Ganon and the very existence of Sheikah (who only appear in the origin and adult timelines). To my knowledge, the only reasons people seem to think the Adult timeline has anything to do with Breath of the Wild are the Koroks, Rito, and the salt mentioning it coming from "the ancient sea." The last one is kind of a stretch, and the Koroks definitely could have descended from the Kokiri in the same exact way they did in Wind Waker (in fact, this is almost a certainty). The only strange one is the Rito, because the only other game they appear in is Wind Waker where they evolved from the Zora. However, there are Rito engravings in Twilight Princess, indicating that they did exist alongside the Zora even at that point. It is certainly possible that they did come from the Zora, just in a different way.
here's my song Otherwise that i submitted for the #cp2077 song contest. enjoy!
squidward