Coming from a Telegraph interview...
“The other thing that’s important to us, particularly with action games like this, is we require a high level of response. The hardware has to provide a stable experience and until recently we felt that we couldn’t get that. But as we saw with iPhone 7 today, the response is good enough now.”
On mobile support
“I love hardware platforms and Nintendo will continue to make our own hardware but what’s changed is that there was a time when Nintendo’s platforms were the most popular in the world and now we see smartphones are the most popular device in the world. So we’ll keep looking for opportunities in smartphones and when we see them we’ll design something specifically for that hardware.”