I've been playing since the Atari days, and have owned every single Nintendo console (minus the Gameboy) to date. This thread specifically covers Nintendo as a software company, so I'll strictly stick to the point. During the NES days Nintendo was more exciting, in that every IP was original. Obviously there was more originality and surprises for what kinds of games they would make next. Fast-forwarding to the 3D era, new Nintendo IPs (major titles) were much harder to find than before. Sure, there were new ways to play Mario, Metroid, and Zelda, but they were still technically the same games from the 2D era.
I had just as much fun with the N64 and Gamecube as I had with NES and SNES. But much of that was due to very strong non-Nintendo titles (even though N64 and Gamecube get an unearned bad rep for weak third party support). Nintendo was at their prime in the NES and SNES days because so much effort was necessary in order to make a name for themselves. Not only that, but Nintendo actually considered their competition as their competition. Creative lulls happen when a company feels they no longer have to be so original (only talking software).
Complacency is a real danger for Nintendo (or any company, for that matter), as long as they put their previous IPs before new ones. They enjoy taking risks concerning innovations in hardware, but their software feels less fresh and less exciting with every passing generation. That being said, it is possible for them to continue making enough money to stay afloat indefinitely, even with no new IPs. However, that train of thought has a negative effect on how all players view video gaming in general.
What makes gaming in this form unique is the ability of developers to offer something the world has never seen. We've all seen Mario, though he never necessarily has to go away. But it's time for a new set of characters to step up and remind us why everyone around the world recognizes the Nintendo name.
