Having been to Okinawa, I have some personal observations on what I saw there.
First and arguably most important, is the fact that I saw a lot of people working well past retirement age.
Taxi drivers in their seventies even!
I went to Okinawa during the Uchinanchu Festival, which they have once every five years to invite back all the Okinawans who emigrated to other countries in the world. My karate Sensei is Okinawan, so us students get to go, as karate being an Okinawan art and part of there cultural heritage.
One night we get to go to this smaller festival party happening down by the ocean, several hundred people there. After speeches and all that stuff, they had there traditional drums other instruments, performing their traditional music. While everyone was standing up dancing this traditional dance. That probably lasted an hour. Seemed heavily influenced by both Chinese and Polynesian.
The people I found there were very peaceful and kind. ( In Tokyo after, not as much)
At the Budokan in Naha, was where they had this huge karate and kobudo demonstrations, and seminars.
At the seminars there were different Sensei in their Seventies and Eighties still demonstrating their Kata and teaching.
At the grocery store, across the road from our hotel. They had a long isle of fresh sea food, some chicken and only a small area selling beef or pork. Opposite to us westerners.
From all the food we ate, a lot more vegetables and a lot less meat than we consume.
There is a lot more western fast food joints in Okinawa now, and especially KFC!
When my Sensei was young, he said there where very few over weight people, and no one classified as obese.
Now there are a lot more Okinawans that are overweight.
I think in the future , you will still see a lot of centurions there still, but modern medicine will play a lot bigger roll then before.
Al