The problem there is DS game can't use the cam and such, and DSi games that do use it cannot run on the DS.Yes it IS possible, look what Nintendo did to the old DS series.
DS+DS Lite no cam and extra things
DSi+DSi Xl Cam+ extra memory+DSi Ware
I see a possibility since Capcom, Konami and SE also offered options to use the CPP and also without using it.