Yup, for certain games they are still going to need buttons for stuff like shooting and picking things up.
Since Natal seems to do quite well already with just tracking a players body it can only be more accurate when it's use with a prop with either glowing or reflective dots on it.
I think part of the problem is that we are so used to controllers that it is hard for us to imagine playing any other way. Using a controller seems "natural" when in fact it is anything but natural.
Personally I find it difficult to use a console controller to play FPS games. It feels like all my intended moves are funelled through a straw. A melee attack is reduced to a single button push. There are so many ways you can perform a melee attack, but
all I get is to push a single button. I used to play FPS games since before the original Doom even came out using a mouse and keyboard on a PC. To me that allows for much finer control. Mathematically, an analog stick results in the 1st derivative of where
you are trying to aim, while a mouse is a 1:1 mapping of where you are trying to aim. Even so, I have gotton somewhat used to using analog sticks to play FPS games.
I think if Natal proves to be accurate enough, and they can reduce the lag to such an extent that it becomes a non-issue (which I believe they can as this is still far from final shipping hardware), that there is nothing preventing game developers from creating
a whole new FPS control mechanism based on body motion that could end up being much less restrictive that a controller. And unlike some people's idea that you will need to "walk/run in place" to simulate walking/running, it can be something much simpler like
leaning in the direction you want to move. I already gave an idea of a motion-only, full control scheme for an FPS while comfortably sitting down on your couch.
The good news is that the developers are now getting the development kits. Let's hope they come up with some cool things that we just can't imagine right now since we are so brainwashed into thinking that these controllers are the "natural" or only way to