It's kind of interesting thinking about how Nintendo will have to proceed past the Wii U. I mean, clearly the Wii U is close to being dead in the water. We can all say "BUT ZELDA AND STAR FOX", but realize those are not the system sellers they used to be. Not by a pretty long shot. Will they each give system sales a small, temporary boost? Sure, but they aren't going to propel the Wii U into the hall of fame. Devils Third? Splatoon? Xenoblade? Those don't seem to have a major Nintendo character name associated with them, and we all know how games on Nintendo consoles lacking Nintendo character names end up. Even if they sell reasonably well, they won't sell well enough, and those three are the least likely to cause an even remotely noticeable boost in sales. They just aren't what Nintendo gamers buy Nintendo consoles for, and the majority of Nintendo gamers do not exit their comfort zone of Nintendo first party games.
All in all, Nintendo has tried to pull the Wii U back, but the Wii U has only sold worse since the first year. I wouldn't say Nintendo has stopped trying, but I'd say they've stopped putting forth their full effort. I figure Zelda U and Star Fox are their last big pushes, and if those don't do the trick, well, "RIP Wii U" will likely grace the walls of Nintendo HQ.
Going back to my first thought though, there has been a trend this generation that has been hard to miss, and that's Nintendo's declining game quality. I honestly don't think Nintendo anticipated the time it would take to craft big HD experiences and set up the Wii U expecting to maintain a relatively even release schedule like they could in the past of all their major first party games. Instead what we've seen is a really sparse release schedule for the Wii U, and oftentimes games fall below expectations. As someone already mentioned, the only truly worthwhile Nintendo developed Wii U games at this point are Mario Kart and Smash Bros. Everything else just reflects Nintendo not having the time to make the games any better. Thus, instead of a big beautiful 3D Mario game, we've gotten versions of the "New Super Mario Bros" series that seem more like level packs than entirely new games. Now we're getting the $40 "budget" games that feel more like a mini-game within a major release than a major release themselves, reflected in either quality, completion time, or both.
Overall, I don't know if Nintendo can really go bigger without third party support that they don't have. As it stands, development is already taking too long to maintain a healthy release schedule for the Wii U, and with no nearly no third party games filling the gaps between releases, there are months at a time without reason to purchase even a single new game, physical or digital. When we see them trying to find ways to fill in the gaps, we get stuff like Mario Maker, Toad's Treasure Whatever, Kirby Blah, etc., which are games that serve only to show off Nintendo's inability to work with the longer development cycles required for their biggest releases.
Of course, maybe Nintendo could deal with it a bit better if they weren't developing for the gamepad and the Wii U itself simultaneously. The gamepad is neat, but besides making the Wii U more expensive than it should be, it likely hasn't been a boon when trying to lower development time on various games.