The funny part is that the AI's didn't do what would in reality be PERFECT for them: go to space. AI controlled craft would be the perfect vessels to send to the moon, the asteroid belt, Mars, and beyond to start creating habitats, bases, mining facilities, sensors, etc. They don't need food, air, and get their energy from the sun and nuclear. They could be all over the solar system and beyond. Or maybe they did and Earth is just a quarantined zoo for humans.