I'm required, by my retirement insurance, to keep both parts A+B Medicare, at a cost of $100 per month, even though I can't use it in Mexico. However, it keeps my BCBS managed state retirement health package alive and, though it wants to be secondary to Medicare, it reverts to Primary in the absence of Medicare coverage outside of the USA. So, up to certain lifetime limits and the usual US insurance procedures, it can work. "Insurance" doesn't really exist in the USA any more.
If you can buy insurance in Mexico, you can decide the deductables. There are no 'co-pay' or 'minimums', etc. in many cases. In fact, the insurance often covers everything, even transportation and follow-up care, medications, etc. Of course, the premiums increase with your age, until you can't afford it any more. You must also buy it when you are younger; often younger than typical retirement age. However, if you retire to Mexico early, it is the way to go; at least until 65 or 70.