By M+ he means WiiMotion+; the forced technology used in Skyward Sword. And really, SS was made as a final bastion for the Wii - to keep people interested because the technology would be reused and refined for the Wii U.
I've been pondering the development time of typical Zelda games, and I figured that two components make up a sizable chunk of the dev time: what art style to use, and how to implement gimmicks. I'll be frank; it feels like Nintendo is doing nothing but experimenting with modern Zelda. They...