@Michael McProuty
As a non-American I know very little about US healthcare - other than it's really, really expensive!
I've always assumed Medicare was the equivalent of a UK or European public-funded health system... but only for old folks (i.e. over 65). But taking a look at Medicare website I'm really shocked by how expensive this retiree cover is.
So I think a big issue about retaining your Medicare coverage while living abroad will be down to how much (if anything) you have to pay, and whether you intend to return to the USA. Medicare doesn't cover treatment abroad, and flying back to USA while sick/injured is typically not very practical.
Even if you take a break, you can re-enroll... and the only downside to this is that there's an annual re-enrollment period (Dec-Mar), so I guess you merely need to plan ahead a bit.
If you don't have to pay anything, then no big deal keeping it in effect. If you pay monthly premiums, this looks like a potentially big cost.
Part A is premium-free for some folks. Some pay $278 or $506 PER MONTH!
Part B is $174.70 PER MONTH!
Both aspects are subject to significant deductibles and co-pays. It should be noted that co-pays for expensive health treatment can still work out to be thousands of dollars.
I'm a legal resident of Spain, Cyprus, and Bulgaria. I like Spain very much, and we have a super apartment in Alicante, but I spend most of my time in Bulgaria. So I have a Bulgarian driving license, and I'm enrolled in the Bulgarian national health system. Bulgaria issues me with an EHIC which covers me for public treatment in any other EU country, including Cyprus and Spain. I could enroll in the Spain system instead, and it would be a little more expensive.
My monthly premium (actually a social security contribution, in my case as "unemployed") is $16 per month (or $192 per year). Issuing the EHIC is free (but I have to go in and ask for it).
There is no age limit (i.e. it's not just for old/retired folks).
There is ZERO deductible.
There are NO exclusions based on your increasing age or prior medical history.
All treatment, operations, prosthetics, and medication is free or nearly free. Any co-pay is minimal. And the cost of treatment is far less than the equivalent in the USA, so any co-pay is unlikely to cause any significant dent to in your wallet.
The Bulgarian system is very interesting as (most) private hospitals are affiliated with the public system, and get a standardized reimbursement according to the specific treatment or operation that they provide. In effect, this means I can get public treatment for a teeny co-pay, or I can have fully private treatment with 20% co-pay. It's an amazing deal, and so far I've only used private hospitals.
Spain doesn't work like this, the private and public options are (as you'd expect) separate.
I've briefly held private health insurance policies in Spain and Cyprus and Bulgaria. Bulgaria was the cheapest (less than $1k per year), Spain the next (less than $2,000 per year), and Cyprus was a bit more expensive than that. Spain public hospitals are pretty good, I certainly don't feel that I NEED to have a Spanish private policy.
In other words, I strongly encourage any American relocating to Spain (or anywhere in the EU) to treat enrollment in your local public health system as a matter of urgency. And get yourself an EHIC and register with your local GP. You will, most likely, be shocked by how cheap and how good public healthcare is in the EU.