Also, at what point do distant relatives of the king/queen stop being called prince/princess? Andrew's daughter is a princess...but will his grandson/granddaughter be called a prince/princess?
Both of Prince Andrew's kids ONLY have the "princess" title because he begged and begged, and BEGGED/DEMANDED his mother allow them to be called that.
Neither HRH Princess Royal Anne's kids nor her brother Prince Edward's kids have the "prince" or "princess" title.
Prince William's kids, who are all now in the the Royal line of accension, have those titles now.
Harry's kid shouldn't and won't have that title...unless Sparkles pitches a fit and then Harry goes to his grandmother and throws a fit. Of course, when Sparkles threw several fits about her wedding and which tiara she wanted to wear, she was denied ALL of that.