To me, Kate Middleton, is not clearly the chosen one. She is 'fiance in waiting' but for how long? How long she can put up with waiting and being on William's beck and call. She is stylish, but is she necessarily empathetic to others less fortunate as Diana was. Diana KNEW what it was like to have family issues, confidence and marital issues, and what it was like on the other side of the Palace. From what little we are shown of Kate in the States, the most we see are glimpses of her leaving a club or walking to and from somewhere, her appearances when William has graduated from wherever, but in reality, Diana showed at an earlier age, true concern and compassion for those less fortunate. One does not have to be 'Royal' to be involved in the welfare of others.
So, my vote, which could change at a later date, to me, Kate will never be a Diana.....