I'll reiterate my personal view of what Nintendo should do from another thread, in a multi-step approach:
1. Buy LeapFrog Enterprises, the makers of the LeapFrog and LeapPad educational devices. Their market cap is only ~$500M and are at a low point now that they're likely able to bounce back up out of.
2. Develop a ~PS4 level graphics horsepower tablet for a 2016-2017 release, with 5" and 11" varieties, running an in-house OS. That is about the same hardware schedule as what Sony's handhelds have been working on, so the 5" could definitely be break even in the $200-$250 MSRP at that point, with the 11" carrying about a $100 premium bump.
3. Use LeapFrog's educational marketing ties, Nintendo's family friendly branding, and a strategic partnership with Panasonic to offer the first major innovation in the smart classroom for Pre-K through grade school. The basics would be a short throw projector, the 11" tablet, and an advanced follow up to the Wiimote that combined will replace the chalkboard/marker board in class rooms with an interactive surface for less than $1000 per room. The expanded package would offer multiple tablets that would connect to a classroom hub, where the teacher could monitor student activity on the satellite tablets from his/her primary tablet as well as enable each tablet to cast it's display to the projector for presentations, demonstrations, etc.. This would be sold as a modular step where even a handful of tablets in a classroom would enable teachers a new level of group project learning tools.
4. On the home/personal user front the 5" would lead the way as a low cost hybrid device with HDMI out (using the same tech as the projector link up) and included HDMI dongle. A controller housing for the 5" would be offered with bluetooth link up and dual analogs, buttons, triggers, etc.. A second attachment would offer a clamshell attachment with second screen for DS and 3DS backwards compatibility. In the living room a dock with included optical drive (for GC, Wii, and Wii U BC) and USB for external HDD to provide expanded storage would be optional. In either configuration you can set the tablet down, sync a bluetooth controller based on the pro pad or a wiimote to the device, and play games as though it where a home console.
5. All Nintendo offerings will be available digitally, including an expansive virtual console lineup.
6. Leverage the Nintendo IPs out into a broader stretch of media, a la Pokemon, with Zelda and Mario animated shows rolled out but directly produced by Nintendo to ensure quality. I'd personally recommend Genndy Tartakovsky to head up a Legend of Zelda series and Hiromasa Yonebayashi (director of Arrietty) for Mario. Maybe bring Tom Warburton in to head up a Wonderful 101 series if they're feeling real ambitious.
7. Service the core gamer on a more consistent schedule and with a more earnest approach. Buy out Platinum and make them first party, have them take over the Metroid franchise and rotate releases of Metroid with more risky IPs (Wonderful 101, Bayonetta, etc.). Hire in a bunch of ex-Sony Liverpool and SEGA staff to assemble an all-star studio to bring back F-Zero as an every four years iterative franchise, offset in an even two years from Mario Kart releases which also joins the 4 year schedule. Take a step forward in the scope of the Mario franchise by offering an open world, free form Mario title that focuses on Mario's core platforming moveset from Mario 64 but set in an expansive and open to explore Mushroom Kingdom. Contract Hidetaka Miyazaki to collaborate with Aonuma on a new core Zelda experience with Souls inspired core mechanics and using Jean Giraud's artwork as inspiration for aesthetics. Bring Yasumi Matsuno in to lead a second team within Monolith.
8. Roll out a line of iOS/Android software that is market specific spinoffs. Pokemon would be a hybrid of traditional (but streamlined) Pokemon mechanics and player v. player arena battles, with a F2P business model, directly attacking the Puzzles and Dragons crowd. A Mario featured endless runner at $5 would be an instant cash infusion for the company. Tilt and finger swipe controls would apply well to a Kirby's Canvas Curse styled title. Animal Crossing and Mario Party would both market very well to social F2P spin off apps. Monetize this market to both build a strong cash pipeline to fund the company's other endeavors and to serve as an IP gateway drug into the Nintendo family.
9. Long term establish partnerships with media companies focused on similar demographics, most notably Disney, to offer them a controlled avenue to their customers. The crowning achievement of this would ideally be Mario and Mickey cross over titles with Mario, Zelda, etc. showing up in Disney theme parks and the like.
The real goal here would be to pivot their hardware business away from the gamer and towards the classroom and younger audience, but doing so with enough hardware muscle in-tact to meet the core gamer's needs and establish themselves as 1. the leaders in educational software and hardware 2. the platform of choice for families and pre-teens and 3. the ideal "second device" for any core gamer at a reasonable enough cost to get them in the door and buying software.