I doubt it. They may be fumbling at the moment but they have too much pride for that. And they can definitely still afford to be in the console market.
They just need to get better support for their consoles and they'll do great again. I can count on one hand the number of Wii U games I like/am interested in. And they need more new first-party IP, definitely. Splatoon was a great step in the right direction but the majority of what they're putting out is still Mario and Zelda and Smash Bros and all that, which is fine and dandy but it means only people that like those specific series are going to buy the console. Personally I impulse bought my Wii U, I wouldn't consider myself a Nintendo fan, if it weren't for the fact that I have nothing else to spend my money on I'd probably never get one.
Well, get a bigger library of (good) games AND stop relying on gimmicks. Can't forget the damn gimmicks. And stop alienating lefties. We're people too, Nintendo. C'mon.
They don't need to change their style to do well in the market, just give us more of what they're doing well. Splatoon is great. It's been ages since we've had a completely new high profile game with that much personality. Give us more of that, Nintendo. Lots more of that.
That'll never happen though, next console will have no screen be controlled entirely by throwing a ball around the room and every game will be Donkey Kong.