One thing to understand when you move to Thailand is the daily Thai baht rate.
For the past 30+ years, there have been some wild currency exchange rates that can affect your spending power.
At or around 30thb to US $1, Thailand starts to become less of a deal.
UK and Australian currencies have been hit hard in the previous years, causing financial hardship for those pensioners on a fixed pension.
Even with 20 year forecasts and careful predictions, there are a host of external and internal activities that can affect the currency exchange rate.
The question to ask yourself if you plan on moving, is what happens 20 years from now if the exchange rate is 20% less?
Can you still financially survive and maintain your quality of life?
I suggest calculating any long term budgets on the worse historical case. That way anything higher is a plus for you.
The good news is that a strong baht appears to hurt the Thai economy as well. So any wild currency fluctuations are quickly addressed.