There's a common fallacy that happens frequently when Silicon Valley technologists start talking about Nintendo, and that is the idea that "their hardware can never compete with the ubiquity of mobile platforms, they should just become a software company and port their games to iOS and Android!"
The success of Pokémon Go, and this new Mario game as well, is showing that Nintendo is taking a different strategy: they're creating custom-made mobile games for the purposes of driving attention and vigor to the main games on their hardware platforms. You can see this with Pokémon: the success of Pokémon Go has been driving sales of the 3DS and the currently-released Pokémon games, and will surely help bolster the hype for the next-generation games that are due out later this year. As far as strategy goes, these mobile games are more similar to the TV shows and movies Nintendo makes than the DS games they came from.
I think this is a good strategy for them. An iPhone or Android will never be as tailor-made for gaming as the Gameboy or DS were, so it's good to see Nintendo sticking to their principles.