Nintendo and DeNA has, up to now, spoken about applying mobile app pricing that reflects the type of game being offered. Social app Miitomo, for example, will be free-to-download but have optional purchases for things like Mii outfits, which is an approach that seems to work just fine for various other smart device apps. It seems, though, that a number of future apps from this collaboration will start off as free downloads.
Takashi Mochisuki of The Wall Street Journal was on hand at a DeNA press conference and shared the following - the full article is behind a paywall.
Mochisuki also shared images of the relevant pages from DeNA's investor briefing handout, which re-affirm - in admittedly hazy wording - that line about free-to-play, and also confirm a number of previously known details about the partnership between the companies.
Naturally it's possible for the companies to change course, as free-to-play / download apps can come in various forms. In addition to microtransactions other options include offering a trial or introduction for free before users pay to buy the rest of the game, such as the approach seen with Fatal Frame: Maiden of Black Water.
With Miitomo coming in March 2016 we have a little while before we can go mobile with Nintendo, though the 12 months that follow should bring at least four more smart device games; it'll be intriguing to follow.