What can Nintendo do?
Simple, do what they did with X and bayonetta 2, but go big and go loud like Microsoft did with the 360 and all those Japanese games they funded and published, as well as that cash they threw at EA and Activision to get day one BF4/COD:Ghosts DLC on Xbox one, as well as the cash they threw to get Titan fall exclusivity.
Nintendo has money, Nintendo has the capabilities to money hat, and in my opinion they need to money hat because 3rd parties at the moment don't give a shit about the WiiU or Nintendo consoles in general.
Nintendo needs to grow the install base, it needs to build relations with 3rd party, it needs to woo 3rd parties by giving them a reason to make games for the WiiU, if that means publishing, funding, paying for extra or timed exclusive content then so be it...this is what a platform holder can do, this is what both Sony and Microsoft have done. If Nintendo seriously wants 3rd party devs, then they need to enter the big boy playing field and start using that money they keep hording.
Remember, Nintendo is the platform holder, it's is their responsibilities to ensure that the install base grows, it's also their responsibilities to get 3rd party on board, failure to do either IS Nintendo's fault and not the fault of publishers or developers, hence me saying that Nintendo fans need to voice their dissatisfaction to the platform holder, Nintendo, if they want change. Again, the best recent example is DRM and its removal by Microsoft from the xbox one, there is no reason the same thing can't happen, but this time to get Nintendo to shell out more cash to get proper 3rd parties on board.
But I guess if you’re happy with the WiiU possibly becoming the next GameCube, or worse, potentially becoming the Dreamcast, then more power to you. For me personally, I want Nintendo fans to experience the same level of 3rd party support I get on my PS3 while at the same time enjoying the exclusive 1st party games that have made us choose our preferred platform in the first place, a win-win situation as it were.
Again, just my opinion so you may take it as you like.