\\Of course, cryptocurrency can never replace the traditional national money of states. State governments will not allow this. And cryptocurrency by its nature is not capable of this. Stable coins can partially displace fiat, but state cash should remain. Even highly developed states with a high level of income of citizens who want to get rid of paper money will still use their non-cash money.
Stablecoin is owned by a private company and that's just really bad if it happen to replace cash. Imagine giving too much power to a company and decentralized cryptocurrency is more preferable if that's to happen.
the problem about stablecoin is also how it's not as transparent as decentralized coin and the company that issued the stablecoin could just print their money even though there are reserved fund audit there's always a hole that can be taken advantage of because it's company owned by someone after all.