Underwater robotic vehicles hold a lot of promise for our nation's military. After all, why have a nuclear submarine filled with people if you can have one that is filled with artificial intelligent systems running everything. The voyages can last a lot longer, as they do not have to stop for food, or deal with the people aboard. So it only makes sense in the future that the US Navy will have robotic submarines, which will most likely be smaller as they do not need living quarters and they will be able to do things that are submarine force can not do right now.
Indeed, there will be all sorts of robotic submarine evasion strategies, which can go along with these new vessels. When a Navy nuclear submarine goes on a voyage no one really knows where it is, this is because "loose lips sink ships" and if no one knows where the submarine is, no one can give away its location. Of course the captain of the submarine knows where the submarine is, and his job is to get lost to the world, and then do his mission.
Robotic submarines could have sophisticated algorithms based on ocean water flows, and random sequencing to get them lost, and put themselves in, and unexpected, unanticipated, and unknown location at all times. Further, Navy robotic submarines could hide behind ocean walking vessels in their wake, or ride up alongside of them. They could shadow a tanker only a few meters from the hull of the ship and be completely cloaked to underwater sonars.
It is even possible that a robotic submarine could shadow a large vessel through the Suez Canal, or other channels, choke points, and even sometimes through the Panama Canal. Now you may say that's far-fetched, but right now we have already produced software which will allow a Navy fighter plane to land on a ship on autopilot. We have also already landed an unmanned aerial vehicle upon a Navy ship or aircraft carrier. We have robotic helicopters which have been doing this for quite a while.
Therefore, I think it would be premature to dismiss this ability, or potential tactic in the future. Not only that, it would be cheaper to produce robotic submarines and autonomous underwater vehicles, and safer. As you could produce lots of smaller units, therefore if one was found out or sunk, the rest could take care of the mission, in a net-centric swarm warfare tactical advantage. Indeed it is my hope that you will please consider all this and develop these future robotic military subs.