Bitcoin can't, but faster cryptos would be able to. The main issue we have are the tx fees and the blocktime.
I totally agree! Hopefully BTC can adjust to be quicker in the future.
For me bitcoin can not replace fiat because bitcoin is not yet legal so how it will happend that bitcoin can replace fiat, And bitcoin now is getting more popular but until now it is not yet legal, so i think even it became legal in years to come it will not be able replace fiat but to do what the fiat can do is very possible in the future.