"Creating a game of the caliber of Super Mario 3D World takes a lot of energy and there is little chance that I could take the time to work on the next Mario. However, I want to get involved again and more deeply in the development of smaller projects, but that doesn't mean it will be a modest download-only title or something like that. It is not impossible for me to work on a new game as the main producer in the future, but even when I’m not directly in charge of a project, I always look at what the teams do in terms of gameplay, and I trust them. Don’t worry about Mario!"
It's not surprising, given recent events (which included Miyamoto stepping down from his position of EAD General Manager), but Mr. Miyamoto has gone on record multiple times that he will not be retiring, instead focusing on different projects. Today's news seems to be an extension of that initial statement.
Considering just how revolutionary his games are, it'll be exciting to see what Mr. Miyamoto has up his sleeve.