I hate to be the one who asks for sources, but you really do need to have some solid data to make claims like "In the very near future only a tiny percentage of the American population will be capable of serving". While my experience is anecdotal, your evaluation does not mesh with it at all, which is that people in the military, even officers, are pretty average or less than average in intelligence, and the PT requirements for the army are completely achievable for a normal person with a couple months of training.
If you've ever interacted with veterans, it's pretty laughable that they are going to "become the new elite". The elite in America has been and will continue to be people who go to ivy league schools for business, finance, or law and then find jobs in wall street, banks, media, and government.