sorry for such a late reply @deathcross
200 years seems to be enough proof for now (USD). But not only dollar survived in a long term, also the Swiss Franc (since 1850) and the Swedish krona (since 1874), some others.
true. there are some exceptions. Most of them however survived that long because country has been in power to "expore" inflation to other countries.
If ww2 wouldn't happen, then USD would never become world reserve currency and would probably be dead by now.
Cheers, Piotr