The biggest expense is usually health insurance premiums, even in your early 50's, assuming that you take good care of yourself. The out-of-pocket max for an ACA plan is something around $6800, much less than premiums.
You could try going to
https://www.kff.org/interactive/subsidy-calculator/ and filling it out for your state, not that you would be interested in the subsidy information, but it also lists average premium (from what I can tell it is for someone around 50) in your state/zip code. I'd multiple the premium x 24 (12 months for 2 people) and then add in $5k each, just to account for something like developing insulin-dependent diabetes which is expensive in an ongoing way.
So for a conservative number, say, $18k for insurance premiums and another $10k for out-of-pocket costs.
However, there is no knowing at all what things are going to look like 10+ years from now. It could be anything from what it was 10 years ago (essentially completely unlimited power to the insurance companies, many prohibitions to getting coverage as a non-employed person, and no out-of-pocket max - but with lower premiums) to single payor.
Hopefully others can refine further on this.