Only just got my Wii U, but for me, it's clear what they need to do.
1) Release at least one Nintendo published game a month from February onwards. Now, I know, they've struggled with manpower and delays, but 2014 is the year Nintendo need to pull out all stops for Wii U, considering they have largely wasted their first twelve months on the market. Starting in February with Donkey Kong, there needs to be a consistent stream of quality Nintendo titles coming to the system. Follow DK up with Yarn Yoshi, Bayonetta 2, Mario Kart 8, Smash Brothers, Fire Emblem vs Shin Megami Tensei, X and more.
2) Promote and announce your software regularly. Perhaps VGX is going to be a good start with a big reveal, though I don't want to bet on it for fear of being disappointed. Do what they did with 3DS and announce/reveal your line up in January and February Nintendo Direct broadcasts so that the information can spread around the web in a quiet period of the year, before financial results come in and Nintendo have inevitably missed targets.
3) Generate more goodwill by rolling out a consistent improvement of eShop, Virtual Console and the fledging unified account system. Why isn't the Virtual Console library as full as the Wii's? That should be rectified. Why aren't there a dozen or more VC games coming out every month, across multiple platforms? Why, when I own the same title across 3DS, Wii etc, can't I use this title on Wii U? Nintendo have access to the best back catalogue in the history of videogaming, and they aren't using it enough.
4) Continue the push for indie titles, but make a bigger deal of it. Sony have generated goodwill by talking loudly about how much they're pushing to get indies on board, and Nintendo, despite having made a strong push, have kept largely quiet about it. Nintendo need to talk about their plans to get more content for Wii U, and they need to continue to dispel the image of them as anachronistic and out of date in the online age.
5) Combine these components to prove that Wii U does have a strong, consistent, quality stream of content across multiple avenues. Don't preach the PR message that you're for the "core gamer", preach the message that Wii U is a console with quality content and prove that by getting your games out regularly. No silly delays, no more lack of promotion--let people know what's coming and when, and stick to it.
If Nintendo do the above they could have a good year. They're going to struggle, because they haven't generated much momentum this year, but it's vital for people who've already bought the Wii U, and the small audience that buy it in the next twelve months, that Nintendo provide as much quality software and improving services as possible. Without restoring some measure of consumer trust, Nintendo will struggle in the future.
Looking to the long-term, there are two things I think they need to do:
1) Ramp up training, hiring and expansion of existing studios, while investing in new studios, acquiring existing studios who have strong working relationships with Nintendo and investing in them, and invest in third party partnerships for specific titles, as opposed to attempting to land multi-platform franchises built on PlayStation and Xbox. Nintendo need more software, but it doesn't need to come from EA, for example.
2) Keep the Wii U supported on the market until 2016, even if the situation doesn't improve. Sega reeled from one hardware disaster to another, and this damaged consumer confidence to the point very few people were willing to invest in Sega hardware. Nintendo's poor track record for rolling out home console software on time, and Wii U's struggles so far, have already done this--but plenty of other people point to 3DS as proof of the good things Nintendo can provide for consumers. Nintendo can't abandon Wii U or its owners prematurely, because it will make launching another machine even more difficult. Keep Wii U and 3DS going as best you can to roll in as much money as you can, and behind the scenes, expand, acquire, build up--and think carefully about what the next generation of Nintendo hardware will do, who it will do it for, and who will provide software for it. Throwing in the towel on Wii U will only damage any successor, as the premature abandonment of Wii has done.