Nice idea..
I don't know many details, but I remember in the original version of Gold an Silver you could do something similar with the Pokémon Pikachu 2 Pedometer (the color one)..
Basically you could turn your steps into points to buy things for your Pokémon..accesories, gifts, items..
For Nintendogs..well..it makes sense, which means that ...no..Nintendo is not going to do it...hope I'm wrong..