Rafael Nadal, runner-up at the Australian Open, and Novak Djokovic, the number one and two ranked players are leading the new age of the two handed backhands which are definitely more dominant in today's game. On the men's side, there are only 12 players in the top 50 who use the one handed while the women have just three in the top 50.
Much of the reason for the two handed backhand rise can be attributed to the more physical nature of modern tennis and to the new strings and rackets which make it the preferred stroke. Until Wawrinka's latest showing, Roger Federer has been the lone one handed backhand to win a Grand Slam in the last decade.
Most youngsters today are taught the two handed backhand which is easier and more suited to the current state of tennis. So while the one handed backhand becomes even scarcer, look at some of today's masters of the stroke.