I'm not buying that at all, over 65s are only about 1/8th of our population. Americans were pretty close to zero population growth when the foreigners started flooding in by the tens of millions, with a huge birthrate.
That may be true right now, but with the huge number of baby boomers reaching 65 every year, that is going to change really fast.
Not to mention the "old, old" population - people who are living into their nineties, and even older, due to advances in medical technology.