GM Yifan Hou (born 1994) together with GM Judit Polgar, are currently the strongest two female chess players in the world. Polgar is rated as the toppest femlae player, while GM Yifan Hou is the ever youngest world chess champion in history, for both male and female (age of 16). They are legendary female chess prodigies who both gained GM title before 16 years old.
Judit Polgar is rated as the strongest female player for many years, but for some reasons she never played in women section and neither has interest competing in the women world chess championship. However, young GM Hou has kept making huge progress and broke FIDE 2600+ recently. Hou also shows great potential to break FIDE 2700+ in last two years international tournaments(her performance rating reached 2700+ and 2800+ for many times!). I bet perhaps within two years, Hou's rating will finally run ahead of Judit Polgar. By that time, women world chess champion won't be a title whether Polgar has interest to take or not, but a title whether she still has promising chance to compete for. It must be an historically fabulous match if Hou and Polgar compete for the next women world championship. Yet, this match might never occur, since Polgar is likely to keep not to compete among female players for lifelong.
PS: Yifan Hou beat Judit Polgar in the 2012 Tradewise Chess Festival. Notice Judit Polgar has not lost to any female player in regular time control tournaments since 1990. Will this make Polgar has interest playing against Hou in a future Women World Championship Match?