Your timeframe isn't from now until you die, its from now until you retire , so unless you're planning to retire at 85, you don't have 40 years of time frame. If you plan to retire at 60, you have 15+ years of timeframe.
You should be clear what kind of risk you are trying to address. When you talk about comparing retiring in Singapore vs a foreign country, you are primarily comparing exchange risk, where your retirement assets and retirement income are in SGD vs whatever currency your expenses will be in. So if SGD weakens vs your expenditure currency, then you are worse off (and vice versa).
Concentration risk is something else, which will affect you whether you are retiring in Singapore or elsewhere - if your retirement portfolio is entirely based on Singapore Inc's success, and Singapore Inc does poorly, as you are concerned about in the long term, then you should diversify your portfolio across other countries or regions.