Imagine if the game never ends up releasing on the Switch. 

It might have been a case of Nintendo themselve having nothing to show, so they paid Bethesda to use Skyrim.

That makes no sense at all. Bethesda wouldn't allow Nintendo to use Skyrim in their advert if Skyrim wasn't yet confirmed to be coming to the Switch. Either Nintendo faked that footage and pretended people were playing it on the Switch behind Bethesda's back, which would be a silly thing to do, or they had permission from Bethesda to include the footage because it WAS being made for the Switch. Betheda would not allow Nintendo to use that footage if it wasn't coming to the Switch because it would lead to the mess we're now seeing. Bethesda are just throwing this out there in order to create doubt so that they can then create hype by verifying it at a later date.

If it isn't and Nintendo used it while Bethesda gave the go ahead, then this is going to be a mess for both of them. For one company to make a bad PR move is possible but for two companies to make a bad PR move seems very unlikely.

That makes no sense at all. Bethesda wouldn't allow Nintendo to use Skyrim in their advert if Skyrim wasn't yet confirmed to be coming to the Switch. Either Nintendo faked that footage and pretended people were playing it on the Switch behind Bethesda's back, which would be a silly thing to do, or they had permission from Bethesda to include the footage because it WAS being made for the Switch. Betheda would not allow Nintendo to use that footage if it wasn't coming to the Switch because it would lead to the mess we're now seeing. Bethesda are just throwing this out there in order to create doubt so that they can then create hype by verifying it at a later date.

If it isn't and Nintendo used it while Bethesda gave the go ahead, then this is going to be a mess for both of them. For one company to make a bad PR move is possible but for two companies to make a bad PR move seems very unlikely.

Remember this box? and the logo shown on stage for the Vita reveal? Sometimes games just don't happen as shown on the reveal of a console, still though, they're working with Bethesda which means there are "games" on the way, even if they aren't Skyrim.

What's wrong with you people? This footage was clearly mounted into the video. Even Zelda BotW and new Mario.

That is not the point of the matter. Whether the footage was real or not I don't know because I'm not an expert. The problem is the fact that Nintendo used Skyrim footage. If the game was not confirmed, Nintendo would have probably chosen another game, not just used Skyrim and risk themselves to be busted moments after the trailer. Too much risk for a game that old. My theory is that Bethesda here has a problem. They will release Skyrim HD for the PS4/XBOne way before this version comes, and they have also to follow Nintendo's instructions of not revealing something before date. And they can't say the game is unconfirmed, because we just saw it on the trailer. So they have to be purposely vague about it, even if it's obvious what is happening.