Bitcoin will never replace fiat cash. A coin everyone mints at the same rate will. It will also replace bitcoin and all of the shitcoins.
Mark my words.
Bitcoin runs off the fumes of fiat.
Most older people trust traditional ways to accept or send payments which is cash but the more influence bitcoin gain over the new population.
And they start using it then bitcoin will become a traditional way to accept and send payments.
Yeah the older generation are still very much in love with the fiats cash, which is a traditional means of payment, though this can't be seen as their fault becasue they are not adaptive like the young, most especially the Bitcoin technicalities. The traditional fiats cash can't replace Bitcoin neither the Bitcoin to replace the traditional fiat cash, this two will consolidate each other for a perfect means of making payment in future.