According to rumor he will be made Duke of Sussex after his marriage.
But he could be given any number of other titles.
By tradition only monarch's children, the wife of the Prince of Wales and the children in the direct line are given the title of "Prince" or "Princess".
Kate is the Duchess of Cambridge and will remain so until her husband becomes Prince of Wales or King, in which case she will become Princess of Wales or Queen.
That’s what I thought
the whole thing is absurd....