I think that Nintendo always has a few games that are "showcases" for any new tech they bring out. The original Wii Sports has often been called a tech demo. I doubt they will release new tech (WM+, DSi) without several unexpected games to showcase them.
It won't be Zelda (though Zelda could be the ultimate showcase for WM+), or any huge AAA title, but it will be more than Wii Sports Resort.
DSi will probably spotlight a few games including some DSiWare titles, or at least one great one.
I think that these games will not be aimed at either the Blue Ocean market or Core gamer market in particular. That is not what matters here. What's important is that the software showcases the possibilities of WM+ and DSi. It will only matter to Nintendo that developers are interested in developing games for the new technology, and that they get positive press for new innovative technology. So what ever is shown will be aimed squarely at that purpose. It could be a Core title, or a Casual, but it will be a showcase for the technology.
