I wouldn't ask the question "if" crypto will replace fiat money, I would ask the question, "WHEN" will crypto render fiat obsolete?
The answer to that question is possibly "Not in my lifetime".
I agree. At least not completely. Government fiat makes up just too much of overall economic transactions for this to happen anytime soon. To put this in perspective, it is estimated that dollar transactions are in the trillions of dollars worth per day while bitcoin related transactions are only in the millions of dollars worth per day.