You've probably seen the rumors by Emily Rogers about Breath of the Wild potentially not being part of the Nintendo Switch launch lineup. Reasons are that the localization and testing will need a lot more time than originally anticipated.
It does fit the picture, though. During E3 2016 Nintendo purposefully avoided confirming a March 2017 release, in fact they kept emphasizing that the game is simply slated for 2017, leaving themselves some room. Emily Rogers was spot-on about many things this year, so I do trust her word. You shouldn't always trust her sources and things change behind the curtains all the time, so these rumors are bound to be inaccurate in some cases. But if Emily hears something from multiple sources, then we should listen... In any case these rumors sound plausible.
And I personally don't mind. I played Ocarina of Time at Christmas 1999 - one year after the original release. That didn't make the game any worse and it's still one of the best games of all time today. Nintendo has gone so far with Breath of the Wild, they might as well take all the time they need to make it perfect, so it will become the timeless experience that is Ocarina of Time. All that stands in our way is our impatience, but that won't matter in two years and certainly not in ten.
In my case I still want to go through my Zelda backlog of Wii U (Virtual Console) games, I want to play Skyward Sword again and I also want to take the time to fully complete both Hyrule Warriors games. So, for me as a Zelda fan there's more than enough entertainment left on the current systems, which is why I can wait a little longer.
A later release also would go perfectly hand in hand with the idea of a Limited Edition bundle, because these Special Edition hardwares and different console colors never appeared at launch. They might appear half a year later, though. So, if this turns out to be true, I will strictly advise any Zelda fan NOT to buy the Switch at launch, because you want to wait for the Golden or Sheikah Slate Edition that comes with Breath of the Wild a little later.