Animal Crossing's explosion in sales should be enough to alleviate people's concerns that Nintendo's business model can still succeed in today's market. The game is selling at a 60% rate to women, many of whom already own smartphones. Women typically account for less than 30% of Nintendo platform owners, so it is indeed a broad market success story and Nintendo should be congratulated as such.
Looking to the future, Nintendo's only real concerns are broadening the market of the 3DS in US/Europe where it is soft, and making sure they keep Wii U sales at a sustainable level where there isn't need for a markdown. The answer to both of these concerns is of course software. Software, software, software.