Seems like the absolute maximum for that is a bit over $1k/month, and that's only if you didn't Medicare taxes for less 10 years, have an income of over $214k/year and get the most expensive part C and part D coverage. A typical amount would be roughly $200/month, less than even someone in their early 20s would typically pay for health insurance.
That’s the number adp.com gave me. Note that it’s like 35 years from now and yes, it includes (I think) C and D parts. Of course a lot of things may change in the next 35 years.