Love this idea! I wonder how this could one day come to incorporate the true value of a coach on deck, which is to see the stroke and offer guidance. Some self-coached or remotely-coached swimmers film themselves underwater, which your system might reasonably consume at some point. I have worked with swim coaches in several formats, and the coach on deck providing instant feedback has been by far the most useful to me. Perhaps this is why one of the most common formats for swimming is the team practice, since one coach working in real time can watch a dozen swimmers and give feedback.
I had the pleasure of learning from Terry Laughlin at a Total Immersion camp in 2014. (I learned to swim as an adult for triathlon.) Terry loved the water so much that we could earn ourselves an extra minute of rest between sets just by asking him to show us a skill again. Far and away my most helpful and memorable swim instruction.