The graphics for Pokémon (overworlds, characters, battle sprites) keeps on getting better. However, I think Pokémon would lose so much feel if it switched to all 3D -- the pixel art somehow kinda makes the games. Their Pixel art improves a ton with every generation, so I can only dream of what Generation V, if it ever comes, will be like with the pixel quality.

Pokémon Rangers sprites were very very good pixel art.