The things Aonuma has been mentioning about Zelda U are an evolution of the major structural change to the linearity (rather, the lack thereof) of dungeons introduced in Link Between Worlds. The rest of the stuff demo'd, going to "anywhere" you see and Epona dodging trees on her own, are more set dressing than a fundamental shift for Zelda.
Majora's Mask was also a fundamental shift but it was clear from the nature of that game it was always going to be a one-off thing (or evolve into its own subseries, like Yoshi's Island.)