It's really just a simple waiting game. There is a strong need for a world reserve currency (currently filled by USD, and somewhat my EUR). Fiat currencies have a 100% failure rate
No they don't.
There are many many fiat currencies currently in existence, and those haven't failed.
Your statement boils down to "Fiat currencies that have failed have a 100% failure rate", which is content-free.
On the same basis:
"Democracies have a 100% failure rate"
"Countries beginning with M have a 100% failure rate"
Regretfully yes they do eventually fail.
If you read through the thread it was suggested that the British pound was the longest lasting and still in existence but the answer to that was ..It is not the same as it was and has been
on the gold standard/ off the gold standard/ decimilization so its not the same fiat even though it has the same name.