Nintendo totally could start splashing a bit of cash for publishing deals, etc. We all know Nintendo keeps a tight reign on it's profits, and while a lot of us weren't happy with the Wii, Nintendo tapped a new market and were totally rewarded with having the most financially-successful console, this generation.
Unlike their competitors, Nintendo aren't loss-leaders. If you don't know, basically MS and Sony lost so many billions on 360 and PS3. For years each console was sold at a loss to the parent company. It cost more to make than they were selling it for (else nobody would ever buy it).
This is a risky strategy which is employed in hopes of enticing people with something powerful and affordable, writing off the losses in order to build a large install base, which in turn leads to profits from software sales. In fact, MS started this trend with the original Xbox.
Now, Nintendo has never done this. It has always made a profit from it's hardware, which is why the Wii has always seemed like a raw deal in terms of money compared to it's more powerful cousins. If Nintendo doesn't want to take such huge risks (to be fair, MS and Sony have their hands in many industries whereas Nintendo relies solely on gaming), that's fine. They could take smaller risks, though.
That's where offering real incentives for companies to issue their big marquee games on Wii U comes in. Don't want to lose billions and billions on hardware losses? That's understandable. Why not pony up much smaller amounts of cash to third parties to get their core games on the console?
It wouldn't even have to be exclusivity deals. Let's hypothetically say that Nintendo approached R* about a Wii U version of GTA V. Let's imagine that Nintendo say "We want GTA V on Wii U" and R* say "We're not sure because of X and Y", Nintendo could simply lessen the burden by offering to publish the Wii U version. This would not involve making the companies not release their games on competing platforms. It's simply saying to them "We'll take that risk for you, now go make it".
If it didn't work, Nintendo would lose some money, R* would be unaffected. I'm sure even a catastrophic flop isn't as bad for Nintendo themselves, as they own the machine and the manufacturing plants, etc etc. They don't need to buy a license to develop a game on Wii. They don't need to buy the discs and cases off of themselves for more than what they paid to make them. Etc.
Maybe it wouldn't be an immediate formula of success. But it would be something that could be built upon. Maybe that could be their strategy of incurring potential losses (they games may be wildly successful), but on acquiring top-drawer software rather than hardware.
It's not going to be an overnight thing. It's been too many years for that. The bottom-line is that if Nintendo want the core gamers back, those gamers need to be drawn to the console. That is done by giving them the games they could not get on the original Wii but could get everywhere else.
Yes, the Wii has the largest install base. But much of those users are casual gamers, which is why companies like R* do not release their games on Wii. There may be a gazillion people who own the format, but how many of them are core gamers? Not many. As has sort of been pointed out, many Wiis are left unused.
You'll notice that while the console itself is wildly successful, the software not so much. The Wii section in my local gaming outlets are smaller than the other two platforms. How often do we see Wii games populating the multi-platform chart? When they do, are they core Wii games, or casual ones?
I'm getting out of my extent of knowledge, here. I really don't have an intimate relationship with sales charts. Ultimately, as Jacob says, if Nintendo really want the core gamers back, they will have to do something about it. Making promising comments and admitting to mistakes is not going to cut it in the long run. It's a good start, but it's just a start.
If they think simply expressing those sentiments is going to bring the third parties and core gamers back whilst they carry on as normal.. well. It just isn't going to be like that. The third parties will give their big marquee games to the platform holders who have been investing in them over the years, and providing platforms where their games sell.
I know I sound very doom-and-gloom, but like some of you guys I would actually like a Nintendo console to be an attractive proposition for me once more. Unlike anybody here (I think) I don't own a Wii, never have, never will (unless some ridiculously good pre-owned deal comes along).
They've made good motions and gestures towards the core gamers recently (I hear they're finally implementing Sony and MS' persistent friends lists.. well done Nintendo), and they should continue to do so. Mere words will soon be unacceptable, though. They need to act. The sooner they act, the better.
They've got a head-start, and if they act now it will be to the benefit of everyone except MS and Sony. If they rest on their laurels, well.. PS4 and Xbox 3 are looming, and will totally and savagely dominate the core market if Nintendo give them the chance.