This is basically what would happen if Nintendo bought Farmville developers Zynga. Alternately, they could just slap a Mario theme on the next Animal Crossing game. Of course, Mario's only crops would be mushrooms and bananas, and his army of loyal toad workers would do all the manual labor for him.
It might be more interesting if they threw in a Pocket Frogs-style mini-game for koopa breeding. What would you get from breeding a blue shell koopa with the winged variety? Two very happy koopas, and millions of very disturbed gamers.