Interview with DeNA CEO Moriyasu confirms that Nintendo's Miitomo is an app for chatting

Those using Miitomo will be able to purchase clothes for their Miis, which is one way that Nintendo plans on monetizing the game. The video game company has some pretty big names as partners in the project, including Bandai Namco and Disney. Considering that both firms don't get involved with something that doesn't have the prospect of making huge profits, it would appear that there are high hopes that this will succeed.
"Miitomo places more emphasis on entertainment. The process of discovering new aspects of your friends via Miis can be quite fun. One distinct aspect of Miitomo is how you can configure your Mii to have it look very similar to yourself. Communicating with friends who actually look like your friends in real life is a distinctly different feeling from text-based communication. We’re thinking of linking the game with users’ Facebook friend lists. I think it could be fun connecting with friends people don’t often communicate with."-Isao Moriyasu, CEO, DeNA
Nintendo plans on marketing the app in the beginning of the year, and it will be launched in March. It might not be the red hot smartphone game that everyone was hoping for from Nintendo, but it is a start.
source: WSJ