Endgame of AI + human gameplay is delegating everything to the AI. I'm not sure how you would have to design a game where you only delegate parts of macro/micro, and still make the game interesting.
I'm thinking it might be a nice playground to just experiment with different game AI architectures.
I've been thinking of trying to combine extremely simple Machine Learning techniques, like tabular Q-learning, with a variety of scripted action and goals. I want to try mixing a lot of really tiny machine learning algorithms (maybe neural networks, but not necessarily) into classic AI scripting and see if it can be more dynamic, but still predictable and controllable. Screeps would be a great testing ground.