No, not by a long shot.
1: They would lose the licensing/publishing royalty from developers/publishers on a platform entirely their own.
2: Nintendo having been forced to become so self-sufficient has made them an expert in creating a software/hardware synergy, their hardware depends on the software and the software depends on the hardware. Something like Wii Sports would not have been possible without a great deal of tailoring to the Wii-mote and would likely never have become such a break-out hit on a foreign platform environment.
3: Nintendo would be subject to hardware solutions, online components, marketing ploys and controller focus that would be strange to them.
4: Besides the Wii U, they usually make a lot of money on the hardware and the peripherals, you won't get to 14 billion dollars in the bank simply as a 3rd party publisher/developer, not in today's market.
5: Nintendo rely on a much higher level of market control than the others, they would essentially abandon all their advantages and lose most of their power and influence.
No way they will benefit from becoming 3rd party. It's unrealistic and horribly minsconstrued as a good option, or an option at all to their current business setup.
