I don’t know the answer to your question about how many additional public courses could be turned into what you describe
I do, however, know that one exists already – – Charleston Municipal. I managed to play 9 holes walking yesterday during the short time when it wasn’t raining.
The renovation occurred during the pandemic. My understanding from speaking with club staff yesterday is they kept the same routing, but the renovation added bunkers and McDonald/Raynor template greens.
I will add the course played very firm and fast, even with a hurricane approaching