Nintendo was recently granted a patent by the United States Patent and Trademark Office (USPTO) that would allow the company to use custom software to emulate Game Boy games on other platforms. The patent lists specific examples such as a seat-back display for airline or train use or even on a smartphone.
Nintendo is in possession of a massive catalog of games that, if emulated and sold in an official capacity in app stores, could likely result in a hefty revenue stream. But unfortunately for gamers, the Japanese gaming company doesn't seem to be interested in doing so.
The new application was filed as a divisional application while the older versions were filed as a continuation. That said, the updated patent is likely just a way for Nintendo to keep the option in the cupboard for a rainy day.
Again, as the publication points out, Nintendo has insisted that they won't be bringing their games to smartphones. Nintendo president Satoru Iwata said earlier this year that their games were designed for their game machines and if they transferred them to smartphones as they are, customers wouldn't be satisfied.
Of course, emulators have been available for smartphones in an unofficial capacity for quite some time, but I digress