Nothing, nothing at all, but i guarantee you if something really smart occurred to me while im busy trying to take all the money i can i would implement it and no doubt that would make people love me :D

If I was the president of Nintendo, the company would burn to the ground as I played the current build of the new Smash.

The handheld business is good enough, at least for now, so leave it alone. If they start entering the "smartphone or tablet" space, they will need to decrease their game price drastically. This, combined with the high rate of piracy on Android will lead to a huge perceptive devaluation of their games value.

What they should do with mobile, is to revive the old first party titles (Gameboy, NES, SNES, N64 etc) and release them for the mobile for a relatively small premium price like $4.99 or $9.99. Meanwhile they should continue their primary mobile market with 3DS and DS, where they are the king of the hill.

On the other hand, on the home gaming system, they are no longer relevant, so it's much more future-proof to be a software publisher. They have been going downhill ever since the entry of Sony first, and even more with Microsoft, and they have little chance to compete against them. Their best bet would be

- Either cooperate with Sony, on the next playstation and release all new Nintendo games exclusively for the new PS platform. It's also a good strategy to release former Nintendo titles with revamped graphics etc on the platform. I am sure Sony can agree upon some privileged conditions with Nintendo.

- Or Just go multi-platform, releasing their franchises on all feasible platforms, the Sega way.

If you honestly think "THE M rated Zelda game people will talk about for the rest of time. No sex or cursing, but there will be gore, death, and a host of disturbing images." is why people like Majora's Mask, then you very clearly do not.

In regards to the Wii U? Support it fully til the end of it's lifecycle no matter what. Jumping the gun and releasing a new system is something that many people on this forum say they should do, but they couldn't be farther off. Look at the Saturn. It's lifecycle was cut short in favor of a new console. This made people wary of buying a Dreamcast, and uninterested in buying a Saturn. Over saturation, and a violation of trust will really hurt you. Support the Wii U until the end, and try to squeeze as much out of it as you can. The situation is grim, but give it the old college try.

In regards to the 3DS? Continue giving that baby support. Don't let momentum die out, and make sure it gets new features, new games, and another revision. This is your moneymaker. Keep it healthy. Make the end of it's lifespan good enough that people will want to buy your next handheld.

In regards to next console?

If you are going to try something drastically different, make sure you have gameplay concepts laid out for it. The Wii U, and even the Wii to an extent, suffer(ed) from a lack of software that really utilizes the systems unique feature. This essentially leaves us with under powered systems that have no real differentiation.

If you are going to battle Sony/Microsoft head on, you have to go all in. I mean ALL in. Revamped online that is on part AT least with their systems. Needs to be at least as powerful as their systems. Needs to have an excellent controller, one that feels good, looks good, and plays good. Most of all though, you need to seduce third parties. If that means moneyhatting, so be it. Do NOT let any notable third party game miss your system. Finally, since this market is hard to enter, your going to have to undercut them on price. Even if it means taking a loss.

In regards to the next handheld:
Just make the best handheld you can sell at 200 at launch. If the 3DS has taught us anything, it's that: A: Nintendo handhelds will sell even if people don't care about the main gimmick/feature. B: Price has to be right, right out of the gate. C. Compelling software right out the gate. Nintendo doesn't need to re invent the wheel here. The 3DS was a screw up in every way, and they managed to turn it around on software alone. Just make a solid system, and bring the games.

I'd wow people again.

Keep trying to fix things with the Wii U and 3DS, but spend the most energy on a new product. Release it when it's ready, not when the market's optimal.

Go third party fast and hard while still supporting the 3DS and WiiU for a while for a nice smooth transition.

Nintendo makes great games that are reason enough for people to buy their OK consoles. But not enough anymore and even less in the future.

Xbox One, PS4, Vita, PC, Tablets, phones and everything else will give Nintendo games the sale they deserve.

Even if game sales tripled, they would still lose money doing that.

(Replace tripled with whatever you want. I'm not doing the math, but it might be around there)

And how do you figure that? 

Besides Nintendo's downhill trajectory gives them a whole lot more to lose than going third party would.

They make a lot of money from fees charged to third parties. Going third party themselves means they stop making money from those fees and have to start paying Sony and Microsoft those fees.