Thing is, if this were to arise, it would probably be in the US or Europe first, no doubt if one achieved it, it wouldn't be long till the other did.
Now, America and Europe are not going to be likely to export this treatment do less wealthy countries for two reasons.
1: No money there.
2: Why would you want to risk people who actively dislike you getting a 1000 year lifespan.
Now, the thing about item 2 is that the risk is around 1 in every million people in the third world have either positive or negative opinions of the US, but that will be enough to warrant witholding the treatment.
So, we now have a situation where a small section of the world is enjoying the benefits of technology and long-life whilst a large proportion of it are living short and difficult lives. It won't take long for that to boil over into something no-one could handle.