A special edition only round Hermès Watch would make perfect sense and one reason to pay such a premium. I definitely want a high end series 4 but always end up leaning toward the ceramics. Feels like I get a little more for my money than a band and a face.
Keep the square ones around but make the Hermès and edition round exclusives. Assuming that there is a round of course. Pure speculation on my part.
I'd happily put my money on Apple never releasing a round watch, just look at Android wearOS running on a round watch, it's awful.