Thought I'd get a thread on this started. Here's what we've seen so far. Looks like links arm augmentation as shown in creating a champion is definitely a thing as shown in the new sneak peak. Wild theories will be abound for the next 12 months or so till the game releases, here's mine: I'm betting on actual time travel, traveling back to a time that's not too long after skyward sword (in terms of Zelda chronology anyway, makes some sense to the HD release) where the islands above hyrule have descended to where they're not that far above it anymore. That's why you "couldn't see them" in botw, because they had completely fallen and were part of the landscape of hyrule by then.