N64 = Where Nintendo lost it.
N64 was Nintendo's answer to the PlayStation. PlayStation only exists because Nintendo was stupid.
After the CD fiasco Nintendo never again had total grip on the video games market.
So, that's how N64 is where it lost itself. They kept their formula set in stone, though. They're still releasing underpowered hardware and relying on programming or marketing gimmicks.
The NES/Famicom had programming gimmicks. They switched to "real" gimmicks with the Wii (Wii remote).
Now that's old, they're having to resort to their IPs to survive.
Edit: Amiibo is a gimmick... Forgot about that... haha