If only it were true. IGN is basing their entire assumption on the fact that you didn't need a GBA in the demo shown at E3. The reason why is because they didn't want to have to have four GBA's connected at each station just to demo the game. That "feature" will be removed for the final version, according to Nintendo.
If they come to their senses, maybe they'll leave the ability to use regular controllers in, but that won't make IGN right. IGN didn't ask anyone at Nintendo, they just made a very poor assumption.