N64 wasn't nintendos downfall, Its very arguable but I would have to blame other consoles. I mean think about it, Playstation probably caused alot of this problem. SNES was ontop of the GENISIS. In my opinion N64 was better then psx (i still loved psx) It had Multiplayer, Great for when your friends came over. Also Xbox, They came out of nowhere. But Its not a bad thing. More consoles being developed all the time. What gets on my nerves is when they make a really good game on a different system and on the ones you own they never release that game for it. In all, I dont think the N64 caused nintendos downfall.