One of the interesting assumptions in this article is that everyone wants to retire in exactly the same way - stay in the same country, live with everything you have now, and possibly better.
However, we have found that every single person we meet has a different dream in life, but that so few people go after that dream. I believe that instead of focusing on retirement as an arbitrary thing you are supposed to do in your 60s, that instead we all stop and map out what is most important in life and then build your savings strategy for that.
For example, we are currently in Thailand where $1,000/month can get you everything you could need plus access to top tier medical care at a fraction of the cost. Now, I realize this is not everyone's dreams but I find this article very generic in it's view on what retirement "should be". Instead I hope everyone stops and figures out what it means to them.
Once you know how you want to live your life you can cut out all the expenses that don't relate to that and use that to fund your retirement, or your dream of starting your own business, or buying a sailboat to see the world. While money is important I believe finding where you are spending that you don't need to can save you more than you may realize.