How so? The original may have gotten good scores, but it sold poorly. Besides, the DS looks like it could be strong for at least a few more years. Especially since Pokemon Black and Pokemon White will be much bigger games (in sales, maybe in reception too). It's still nice to be getting a game like this late in the DS's lifespan though.
Stratos, as Shaymin said, the game is not out yet. It has a vague "2010" release date for Japan and a 2011 release date for other regions.