You may not know how frequently one specific participant will utilize Medicare, but you can estimate by cohort. How much will it cost for 65-69 year-old, 70-74, 75-79, etc. Then calculate the changes in the numbers of each group, and you have a decent estimate for the whole Medicare population.

I am suspicious as to whether he is looking to cap costs by reducing what medicare covers, pushing more costs  onto the Medicare Supplement programs that seniors have to pay for themselves.