I think we'll start seeing the mini-game games start to slow down. I think there have been a lot of them so far because the devs are learning to work with the hardware, and the mini-game style is very conducive to gaining experience working on a lot of different things, if not working on any of them in-depth. Also, since the whole motion control thing is pretty new in the first place, players themselves are still having fun with all the random things you can do. As devs get more comfortable with the hardware, and the things they can do with it over the course of a "normal" game, and as players move past the initial "wow" factor of motion control and begin to want something more, we'll see the mini-games get much less frequent.

Of course, there will still be a new Mario Party game each year until the end of time...