Nintendo isn't going anywhere soon! They have proven to survive through some of the worst downs the gaming industry has had, as well as Nintendo having a strong following due mainly to its seniority and the amount of people out there who started with Nintendo, and will most likely stand by Nintendo the rest of their life!
As i grew up i started playing Playstation, simply cuz they made games for a Maturing Audience like me, but at the same time, that wasnt all i wanted, i still wanted to stay up to date with the classic characters i grew up with. So whereas i have moved on, i still have had all the Nintendo Consoles just so i can keep playing things like Zelda, Mario, Metroid, Donkey Kong.,.. i could go on!
So yeah i would be more worried about Microsoft dropping out before Nintendo! If only we could get so lucky, that Halo could start coming to other consoles! Cuz in my eyes, Halo is all Microsoft has to win a console race!