But yeah, surprises can happen so interesting times.
Why are you making it sound like EU is a third world country? Are you aware that living standards are higher in many European countries than the US, right?
If we measure the total pie then its much smaller in Europe than in the U.S (I mean total wealth/gdp per capita). Only small countries like Norway or Switzerland have high gdp, in France or Germany its almost 50% lower than in the U.S.
Now the pie does not distribute equally in the U.S that's true, but still, there are tons of millionaires in the U.S and I mean pretty regular people (doctors, finance, software devs etc) that had they lived in Europe they would have been comfortable and nothing more. think something like 100k Euro a year (at best) instead of 3-5 times as much which is what they make in the U.S. If the U.S loses reserve status there just won't be enough money to go around for those salaries, or if there will there will be a horrible inflation, either way it just wont be sustainable.
P.S - lots of middle class people in the so called rich European countries like Germany or the Netherlands cannot afford heating anymore. So no, it is definitely not third world but its also not particulalrly rich. The main advantage though is Europe has mostly free healthcare and the U.S is an absolute mismanaged mess in that regard.
But it is certainly the case Trump is trying to bring US income down to something closer to EU levels, which will hopefully cause Congress to get its spine back.
The UK is reconsidering. If the bloody UK is not confident, who else would be? They might be too tight inside for now, but that is a strategic weakness and it will only go one way. Short of the US making it a satellite, it will only loosen.
Why do you think that the standard of living would become better after losing reserve?