I don't think they should concentrate on becoming number one but on becoming profitable in third place. To do that they need to get back to making profitable hardware. People complain about the kinect pushing prices up but the wiiU pad has meant the console itself is not up to scratch and dearer than it should be plus I still haven't seem any uses that justifies the compromises brought about. I also think their decision to stick with powerPC architecture was a disaster as it just puts one more reason for third party developers not to make ports which really hurts it's chances in a one console household.
Also I don't know how they run their company but from the outside it seems to be massively inefficient. They can't afford on any level to have games coming out a year or more after everyone is expecting them. I know everyone complains about merciless publishers crushing the souls of developers, which to that extreme is bad, but it seems like, on both the hardware and software front Nintendo is running itself as an indie developer, doing exactly what it wants to in a time frame it wants to with no regard the business side of things. Stop thinking "that's cool we should do that" and put their business hat on. It feels like Nintendo is the last gaming company, rather than a business that makes games, and in this market that is not going to cut it. Having said that the Wii and DS made a truck load of money - more than enough to keep Nintendo afloat until their fad console so I really don't see them leaving the hardware market. In fact I think they'd be least likely of the three (MS being most likely - at least to sell xbox off not just shut it down. I could see if they had a change of management them streamlining quite drastically and concentrating on selling business sevices with just core products of windows and office left on the consumer side)