One thing to consider I think is that we can see that the Zelda demo may have been an older build of the game. This can seen by one neat detail: on the newer build, which was shown on Jimmy Fallon and on the Treehouse livestream, you can see a weather forecast on the HUD, while the WiiU demos of E3 2016 did not have that feature. The Switch demos also lack this detail, which would suggest the demos are not recent but a few months old. It would make sense that other games would have older demos in the same way, so there is a bit more time than just from now to their respective launch dates.
Edit: This is not correct, it turns out the demos do in fact have the weather forecast (though it is not present at all times, only in certain moments of the demo). Disregard please.