basically what it says on the tin, what if Edward, The Duke of Windsor had a son with his wife Wallis, Duchess of Windsor? what effect on the Monarchy and the British public would this Duke have?
If said son receives the title of Duke of Windsor is entirely upon the Monarch.
did my best to find this, but I think you're thinking of the honorific "His Royal Highness" which King George VI gave back to his brother but restricted so that his wife and any future children wouldn't get, the title however would as far as I can tell be passed down to any sons