As you probably nintendo will make a bigger ds. Almost the size of an psp.
It was already pretty big for a handheld just getting a tad bigger.
 
 
I'm sorry for posting this so late but I forgot about this blog a bit.
Nintendo announced PokePark Wii: Pikachu’s Great Adventure at their retailer briefing in Japan, but the only detail mentioned was that it’s releasing on December 5th in Japan.  Pikachu is an amusement park with friends and you battle and such against may different varies of pokemon.
 
 
The official site of Nintendo has confirmed this new DSi. The screen of the Nintendo DSi LL is 4.2 inches, and it will come with a larger stylus. It will be sold for ¥20,000 starting Nov. 21, and will come in the colors
Red, Brown and White. This device will be titled the Nintendo DSi XL in North America and Europe, being released sometime in Q1 2010.

source. bulbagarden.net