It's kinda weird having the 5th Generation on the Nintendo DS, since the Nintendo DS will might be the first handheld in history to ever have two generations on it.
If it's gonna be on the Nintendo DS... then that would mean... all the model layouts and all that will be the same. And they will use both overworld and battle sprites once again. If only they announced the Nintendo codename 3DS at last E3. Or what if they have actually announced the 5th Generation too soon?
But anyways, I'm sure all the mapping style will be exactly the same as the 4th generation. No difference whatsoever, which kinda sucks really, I was expecting more from them.
I kinda wish I was a programmer, that way I would be able to create my first 4th and 5th Generation map editor.
EDIT: If it really was on the 3DS... Pokémon Sunday would have no choice but to leak the info and the looks of the Nintendo 3DS. And I'm sure Nintendo wouldn't want that.