I haven't researched this. But does it really go down when you consider the supplemental ins you need to buy for part B(? or whichever letter it is) and for drugs. My mother 92 pays 170/mo for the supplemental plus the medicare premium (I don't know the number - maybe she is on medicaid, I don't remember).
170 - 2 supplimental policies
254 from the web site
96 part B
520 total
That 520/mo. is a good policy for a private ins. policy today.
Check the numbers - I'm not sure if I got it right.
https://questions.medicare.gov/app/answers/detail/a_id/2260/~/medicare-premiums-and-coinsurance-rates-for-2010
I have ten years to go until 65. Again, without doing/knowing the numbers my guess is that my age 65 costs will be close to my age 64 costs. After that I'm guessing by the time I'm 70 we will have a single payer system. My costs will then go down or be pretty flat as I dump the costs on the younger generation that is still working.
Maybe others can contribute with their experience.