You mean Pac'n'Roll, and Pac-Pix? Yeah, the ideal game would be Pac-Man DS! It could have Pac-Pix, Pac'n'Rollm and a Nintendo DS adaptation of Pac-Man VS. *beam*
But, depending on the price point of Nintendo DS game right now, having Pac-Pix by itself could be just fine. If the prices of Nintendo DS games are low (which they should be), gamers will buy more games. Imagine going to your local game store and leaving with 3 or 4 Nintendo DS games in one shot. Also, Nintendo Power magazine can include demos, since the new media (the game cards) are cheap enough to produce. They can keep the price low and still proft, yet, they can also not worry about giving demos away in promotion.