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There is no easy fix for Nintendo I don't think.
Motion gaming isn't that popular anymore. All the motion gaming IP are dying or dead, with Just Dance being the last of the lot. Motion gaming also didn't cross over past casual-style/reality based gaming (ie: dancing, baseball, fishing, tennis, etc.) ... people didn't go crazy about motion based Zelda or Metroid or Red Steel 2 or Star Wars (Kinect) once the inital hype wore off. It's just a craze that ran its course, today casuals are more interested in smartphone/iOS gaming if they want to game with simple/easy to play experiences. They dominate Nintendo on price/selection too.
Cartoony games are not vogue right now either outside of the smartphone/tablet market where they dominate. But on consoles/portables they're not doing that great, even Sony is finding it tough to sell things like LittleBigPlanet and Tearaway.
Japanese console industry has imploded. This hurts Nintendo the most.
Portable gaming is declining because kids/parents are getting their fix from cheap iOS/tablet gaming.
Console gaming is become the relam of big budget, big TV experiences for Western consumers primarily ... something that doesn't play well to Nintendo.
You have big budget console games on one end of the street (Uncharted, COD, Battlefield, Batman, Destiny, etc.) and then you have mobile blockbuster break outs that are cannibalizing the "I just want to play some simply, fun video games" crowd like Candy Crush Saga, Plants Vs. Zombies, Angry Birds, etc. but in the middle has become squeezed out of the equation more and more. Mario can still live there, but not many other IP can anymore.
Nintendo's had an incredible run (30 years in the console space is amazing), and they still make great games, but I question their ability to compete in this environment. They are stuck in a series of dead ends. Maybe the sea tide shifts a little allowing something like Splatoon to become a big hit. I think Amiibos will be successful for them financially though.
