In a way, they already are. Look at the architecture of GANs, which use a secondary model to judge the quality of response from the first one. It's not used for

In a way, they already are. Look at the architecture of GANs, which use a secondary model to judge the quality of response from the first one. It's not used for training, but it's a good and simple example of how models can be composed to build something more advanced.