Middle stage between baby and adult mobs

With the announcment of the new baby mob models, i think that it would be a cool idea to repurpose the old models as a middle stage between the babies and adults (with some minor changes to body size), for the rabbits, the old adult abbit models could fit as middle stages too due to the size change between the new and old. The "teen" mobs would drop a bit less but would still drop items. I think this would make the minecraft world feel alot more complete and make the mobs feel more complex.