Almost nobody would buy a Nintendo home console then. Look at the Wii U. It sold 13 million units 3.5 years. Nintendo has almost no customers left. If they launch it when their competetitors release new hardware it will be the next flop.
It's 4 years since it's the end of the year and no, NX will be a totally different scenario, Nintendo messed up big time with the Wii U but it doesn't mean that they are doomed, if they have solid advertisement, a totally new name for the console, on par specs with the rival consoles if not better and a couple killer apps at launch Nintendo will be just fine with the NX and from the leak I previously linked we already know that NX will launch with Zelda U which is a killer app