I agree this is the current demographic trend, but I dispute the notion that what today is considered "Orthodox Judaism" has been normative throughout Jewish history.
It was taught to me by a very great teacher that at one time the 'Sadducees' represented a majority of the Jewish population, and at a later time, 'Karaites' represented a majority of the Jewish population.
Of the Sadducees, no one remains. Of the Karaites, the number remaining is in the thousands, and they are irrelevant to Judaism whether or not they are considered Jews.
http://tarkus.pha.jhu.edu/~ethan/jFAQ.html
"...the genetic evidence supports the notion that the Ashkenazim are descended from a small ancestral population...estimated by Risch et al. (1995) to have been as small as several thousand people about 500 years ago..."
If half the Jews alive today come from as few as 5000 Jews as recently as 500 years ago, it does not matter who is currently in the majority or even considered 'normative'. Whose descendents will be Jewishly thriving 500 years from now?