Milbank Quarterly (December 2009)
Aging in America in the Twenty-first Century: Demographic Forecasts from the MacArthur Foundation Research Network on an Aging Society
S. Jay Olshansky, Dana P. Goldman, Yuhui Zheng, and John W. Rowe
Context: The aging of the baby boom generation, the extension of life, and progressive increases in disability-free life expectancy have generated a dramatic demographic transition in the United States. Official government forecasts may, however, have inadvertently underestimated life expectancy, which would have major policy implications, since small differences in forecasts of life expectancy produce very large differences in the number of people surviving to an older age. This article presents a new set of population and life expectancy forecasts for the United States, focusing on transitions that will take place by midcentury.
Methods: Forecasts were made with a cohort-components methodology, based on the premise that the risk of death will be influenced in the coming decades by accelerated advances in biomedical technology that either delay the onset and age progression of major fatal diseases or that slow the aging process itself.
Findings: Results indicate that the current forecasts of the U.S. Social Security Administration and U.S. Census Bureau may underestimate the rise in life expectancy at birth for men and women combined, by 2050, from 3.1 to 7.9 years.
Conclusions: The cumulative outlays for Medicare and Social Security could be higher by $3.2 to $8.3 trillion relative to current government forecasts. This article discusses the implications of these results regarding the benefits and costs of an aging society and the prospect that health disparities could attenuate some of these changes.

this is not a good idea
Medical costs are lower for people in Medicare--moving 65-67 year olds out of Medicare means spending more money on them in the aggregate. Lowering Federal health spending by raising total health spending isn't a good tradeoff.
Is that $3.2 to $8.3 trillion
Is that $3.2 to $8.3 trillion in real terms? In present value terms?
Reply
Unfortunately, I was unable to acess the full article so I don't know. Generally speaking, such things are presented in present value terms.
I, too, didn't see access to
I, too, didn't see access to article at your link (which is why I had to ask about the figures). But I just found it available online free with (free and immediate) registration at http://www.biosciencetechnology.com/News/FeedsPubGet/2009/12/sections-in... Click "Register" to register and the article may appear (as it did for me); if not, I assume a search on title will work.
Those numbers are apparently in real terms (constant 2007 dollars), but not present value. The quote from page 856:
These estimates suggest that federal outlays for these two programs [Medicare and Social Security] together could be underestimated by $3.2 trillion to $8.3 trillion (2007 dollars) relative to current government forecasts.
Squandering the longevity dividend.
Increasing longevity is a HUGE possible windfall, and we are squandering it through a horrible state pensions and benefits system. Instead of using it to add more productive years, we are using it to add more years of negative productivity.