G. Mark’s Answer
I spoke to my sister, who is an engineer in this particular field. She described what they did. I also worked on a project for automating plant operations using various computer tracking techniques. The bottom line is that it will be entirely roboticized. Look at pictures of the inside of the Amazon warehouses. See the video on how the material is sent automatically to drones for delivery by the robot mini-plane. I believe the test be is in the UK, possibly around Surrey. Now with AI and Machine Learning, the robots will be able intelligently decide how to handle novel packages. Essentially all that will be left for human staff would be to teach the robots when necessary and provide maintenance. AI will also be able to do predictive preventative maintenance and minimize the number of staff required to monitor the system. Materials handling engineers will be predominantly maintenance techs and AI and ML engineers. Reprogramming the units for new products will also be minimized, and the machines will gradually build up a Big Data resource to allow it learn about a new product's characteristics autonomously. Voice interfaces and data interfaces to the system will allow it to request its own maintenance, most likely before an actual failure.
This will make "working in a warehouse" a truly high-skill and most likely very high-paid occupation. And what an individual learns on this job will be applicable to a tremendous number of other fields.