I see that the progeny of the Duke and Duchess of Cambridge (aka Harry and Kate) will be known as His/Her Royal Highness the Prince/Princess of Cambridge - a new title.
Unless you’re aware of a MAJOR scandal brewing, I think you mean William and Kate.
And it’s now been corrected to note that the title has been awarded before, just not in more than a century. Apparently any child of the Duke and Duchess of Cambridge is Prince/Princess. It’s just been a while since there was one…
“HRH Prince(ss) _______ of Cambridge,” not “the Prince(ss) of Cambridge.”
And it’s not being specially awarded. As of earlier this year, any child of an eldest son of a Prince of Wales is a prince or princess, and any prince or princess who is the child of a peer uses their parent’s title. (Before this year, it was only the eldest son of the eldest son of the Prince of Wales. All of the others were styled as the children of dukes. Lord/Lady Firstname Surname. Although it never actually happened because William is the first eldest son of a PoW to reproduce since 1917 when the current rules were written.)