Breath of the Wild already references Skyward Sword, Ocarina of Time, and Twilight Princess in a voiced cutscene, and makes further references to Ocarina in the Zora tablets and with Urbosa’s dialogue. The events of those games are firmly in the backstory of Breath of the Wild, even before you take into account that Tears of the Kingdom introduced the previously amiibo locked items directly into the base world with a lot of prominent framing. Heck, characters directly reference these items in written dialogue. It can’t be written off that BotW/TotK are directly in continuity with the earlier games.
That voiced cutscene
vaguely references what brings to mind SS, OoT, and TP,
in addition to ALttP and TWW in that same speech, which shouldn’t be possible if it’s truly the actual, exact events of those games that are being referenced. Also, as I’ve pointed out multiple times in this thread already that everyone seems to conveniently be ignoring, the event that both BotW and CaC originally led us to believe was supposed to be OoT with Ruto and Nabooru facing off against Ganondorf,
who was explicitly said to be the original source of Calamity Ganon, was actually
not OoT as we know it at all, because TotK shows us that the source of Calamity Ganon is instead a
different Ganondorf during a
different Imprisoning War—meaning the sages we thought were OoT Ruto and OoT Nabooru must be different characters entirely as well, with the obvious implication being that the Zora and Gerudo sages of TotK’s Imprisoning War are named Ruto and Nabooru, which also explains why the Divine Beasts are named and modeled after them. So, no, the current canon is clearly that it’s
not OoT that was being referenced, which was previously the only game aside from SS that seemed to be explicitly referenced in a tangible way.
Put that all together, and BotW/TotK would need to exist in some sort of world where (some of) SS happened, but OoT as we know it did not, which can only really be an alternate timeline, likely splitting from SS. And if we’re to assume things like Zelda’s speech from BotW vaguely referencing SS, OoT, TP, ALttP, and TWW, and other references of arguable canon importance like minor location names and previous DLC/amiibo items referencing games across all three timelines as well are indeed supposed to be canon despite being contradictory, the simple explanation is that events
similar to these games happened in the new, unexplored timeline’s history (and I believe that’s exactly what TotK strongly implies with its obvious OoT parallels), which is really the only way to make it make sense without impossible nonsense like a Dragon Break inexplicably merging timelines on an enormous scale, or the same idea (that similar events to games played out on another timeline than the ones we know them to take place on) but more convoluted, with essentially the same thing happening but instead of branching off SS it happens far into the future on one of the existing timelines, which just raises more questions all around.