No, he said the Mario and Zelda teams are working, not that they're working on Mario and Zelda games. Of course they're working! It's not like they sit around doing nothing between games. Remember that Mario Galaxy was made by the DK Jungle Beat team. I think they're always playing around with what to do with the next Mario or Zelda game in any case, like the Mario 128 project, but that says nothing specific about future releases.