They can't drop dual screens, then it wouldn't be backwards compatible with DS games which would be sucky. I don't want to have to carry both my DSi and my Super DS around with me.
Additionally, the dual screen design is very useful for many kinds of games.
A game I'm developing with some friends:
www.xnagg.com/zombieasteroids/publish.htm
It is largely a technical exercise but feedback is appreciated.







