Well, now more than ever I'm rooting for the Queen Consort title because it would be a shame to not see that piece for a long time! What other pieces are specifically designated for future queens?
It's never been publicly disclosed, with the exception of Queen Victoria's will, which pieces were designated as belonging to the Crown to be worn by all Queens in right of it.
Victoria designated the George III Fringe Tiara, the Oriental Circlet, her diamond jubilee necklace, the George IV Diadem, her diamond collet parure and earrings, the William IV diamond bar brooch and a few bracelets as Crown pieces.
Queen Alexandra died without a will and her jewels were divided up privately among George V and her daughters. The King took as his share all of the jewels received by Alexandra from civic bodies, peeresses of the Realm, Queen Victoria and her wedding gifts from Edward VII. Many of these jewels are believed have been designated by Queen Mary in her will as belonging to the Crown.
Queen Mary assembled a huge collection of jewels in her long life, both purchased outright and gifts from the very wealthy Indian princely rulers during the Durbar. She also received jewels from Queen Victoria, Queen Alexandra and Edward VII upon marriage. And yet more from George V throughout his reign and civic officials. She also inherited her mother's Cambridge jewels, including the emeralds when her brother died.
Queen Mary later assembled parures of both family jewels and her own jewels for the marriages of Prince George and Prince Henry. The current Duchesses of Gloucester and Kent both wear these jewels today. Princess Michael and Alexandra more or less wear jewels given to Princess Marina after her marriage.
The Queen Mother was never particularly interested in jewels, so she wore the same pieces over and over again from the Crown Collection, like Alexandra's pearl and diamond parure, the William IV Brooch and diamond bar, and the Oriental Circlet. She wore the George III Fringe Tiara in her earlier years as Queen, but later switched to the Boucheron Tiara after it was augmented by Cartier with the arches.
Queen Mary gave Elizabeth the Delhi Durbar diadem as a personal gift, which she wore once to a state visit to South Africa, and then it was never seen again. This was extensively altered to be worn as a tiara and given to Camilla as a wedding gift from The Queen.
The rest of Queen Mary's jewels were left to The Queen as both personal gifts and designated for the Crown. The Queen Mother left all of her personal jewels to The Queen with the rest being returned to the Crown.
The Queen is also likely to designate pieces she has received throughout her reign on behalf of a State, such as the Brazilian Aquamarine Parure and her diamond necklaces from the Saudis, as belonging to the Crown after her death.