Cumberland Sauce

Whatever Royal Dukedom is resurrected for Prince William's marriage, it will not be Cumberland, since that one has never been suppressed. The heirs to the Traitor Peers reserve the right to petition for restoration to their titles. 2014 would be a good time to restore them of the Queen's own initiative. Princess Caroline of Monaco as Her Royal Highness The Duchess of Cumberland and Teviotdale, Countess of Armagh, Princess of Great Britain and Ireland (her Hanoverian husband still uses the title "Prince of Great Britain and Ireland", which is not a peerage)? Why ever not?