Being a Nintendo fan, and knowing their history, they'll die before releasing their software on another platform other than their own.
Now I myself, pretty much stopped playing handheld console games quite a few years ago, but can honestly say that touch-screen games with ya fingers **** me, and a lot of others. People like me prefer to play a game with physical buttons, leaving the whole screen viewable at all times. Now casual games wise, sure, iPhone for the win, but anything else, there's always going to be a market for a DS/PSP type console.