No, the meaning of the phrase "living beyond one's means" doesn't go to the unavoidable fact that circumstances change over time. I will one day become infirm and unable to earn money, that does not mean I'm currently living beyond my means.
US dollars might one day cease to be the global reserve currency in which case Americans will not see such benefits associated with that. This is a true statement. That doesn't mean they are currently living beyond their means either though.
> I will one day become infirm and unable to earn money, that does not mean I'm currently living beyond my means.
That is not the same thing because it's real productivity, labor is the only thing in the world that has any real value. You're exchanging your own labor for other people's labor. The US is exchanging something that has no inherent value (USD) for other people's labor.
If I take on all the debt that I can, max out my credit cards, mortgage my house, and spend everything I have on luxuries, am I living beyond my means, or am I living within my means as evidenced by the fact that I'm actually doing it?
US dollars might one day cease to be the global reserve currency in which case Americans will not see such benefits associated with that. This is a true statement. That doesn't mean they are currently living beyond their means either though.