No offense but I think the Ganondorf = true hero of 10,000 years ago is as dumb as the Ganondorf being Link's father theory that a lot of people were believing in before BOTW's release. And all because Link had a blue and red striped design on his shirt's collar that looked like the design on the Gerudo's crop tops. Turned out it meant nothing.
I'm not saying it can't be a major twist, if they explained it right. Just a really risky, bad one that would make equating Link with the ancient Hero image in BOTW and AOC lose its meaning. The ancient hero is meant to be Link, just as the ancient princess image is meant to be Zelda. It's, like, on the game card. XD It'd be really messed up if it turned out to be Ganondorf and Zelda instead. XD
I am very interested, though, of course, to know how mummy Ganondorf got sealed. And who that hand is...