With everything in the world, there will always be somthing that comes in the future to replace the ones that exist, like what happend with fiat years ago that came to replace gold, bitcoin and cryptocurrency are here to replace firat, and who knows in the future another faster and better system is gonne come and replace cryptocurrency, but you have to keep in mind that we are still in the first life cycle of the bitcoin and cryptocurrency so there is a long way to go, before it gets replaced.
fiat have replaced gold as a primary currency but gold was still alive and useable till now . cryptos are here but they didnt replaced fiats .
your assumptiom could be wrong ? well lets find out after a long time but in the future if ever theres any new method for paying ,
cryptos could still exist like what happens with gold . we dont need to worry
No one can predict on what would be the future but seeing on how crypto is really relevant in the essence of payment system specially its decentralized most likely then we can really say that it would take more longer.
Crypto wasnt created on replacing fiat in the first place but rather do really start out on being a new payment alternative system which is opposing centralization and of course it cant really be avoided on having
that kind of impression on where they do believe that this could replace the current payment system which i could say that it is really impossible for it to be replaced.
They would rather both exist and do serve out different markets because we do have different preference and both could exist on the same time.