Royal dukedoms interest me. Their history is already well documented; however, as usual, I shall endeavour to condense the facts down to their essence.
When a royal peerage is conferred upon a royal prince or, indeed princess, and it subsequently becomes extinct, it is then reserved for a later prince

and is unavailable to a Subject.
The royal dukedoms of York and Gloucester were both created in 1385. Since 1474 the dukedom of York has traditionally been reserved for the Sovereign's second son.
The Dukedom of Edinburgh was first bestowed on a grandson of King George I. Queen Victoria made her son, Prince Alfred, Duke of Edinburgh; and, like Prince Philip - the current Duke - he, too, was a sailor prince.
The Dukedom of Kent was originally non-royal. The Greys held this title until it became extinct in 1797. It effectively became a royal dukedom two years later, when King George III gave it to his fourth son.
Other royal dukedoms include the Dukedom of Clarence, derived from the Honour of Clare in Suffolk; the Dukedoms of Cumberland and Albany; the Dukedom of Kendal; the Dukedom of Sussex; the Dukedom of Connaught; and the Dukedom of Cambridge.
Since the Dukedoms of Albany and Connaught no longer pertain to the Realm, they may be considered virtually extinct. The Dukedom of Windsor was created especially for HM King Edward VIII following his abdication; so, though technically vacant, it is unlikely that this title shall be revived.
The Dukedom of Cambridge was re-conferred as a marquesssate in the 20th century which has since become extinct; so it is possible that this royal dukedom could be revived one day.
The Duchy of Lancaster has been merged with the Crown; and the dukedoms of Cornwall and Rothesay are used by the Heir Apparent.
It has been proclaimed that, following the deaths of his parents, HRH The Prince Edward, Earl of Wessex shall become The Duke of Edinburgh.
Paul James wrote
an interesting piece about royal dukedoms in 2004.
Whilst it cannot be discounted that a new royal dukedom could be created, the most likely dukedoms to be re-conferred in future are those of Sussex, Clarence or Cambridge. There has, indeed, been some speculation that, on the day of Prince William's marriage, such a title may be conferred.
Prince William's bride would otherwise assume the style
Her Royal Highness Princess William of Wales.Last published in June, 2009.