One of the suggestions is outright prohibition, doesn't seem like it's the most likely candidate.
There is a zero percent chance that stablecoins will be banned, if that's the case, you'll have to ban practically every other derivative instrument too. Goodbye futures, options and swaps for all markets, not just cryptocurrencies.
These are basically derivatives of fiat, just like people trade futures for wheat, oil and gold. Some futures are physically delivered, just like how stablecoins can be redeemed.
They're just feeling threatened, and who can blame them!
I guess that central banks are starting to "feel the heat" of the crypto/Blockchain revolution. They don't want people to use an alternative financial system that's decentralized by design. After all, they want to maintain power/control over the world's economy. Since decentralized cryptos cannot be controlled, they become a threat to the existence of the current monetary system.
I don't think that central banks will succeed in "phasing out" stablecoins in their entirety, but they could encourage governments to regulate the industry more thoroughly. Decentralized stablecoin solutions will remain untouched, but those offered by a central authority (like it's the case with Tether and Binance USD) will be the ones heavily impacted by fierce regulations imposed by governments worldwide. This is good for the end user in the sense that corruption and fraud is reduced at a minimum. No matter what governments' efforts may be, they cannot disrupt decentralized alternatives to existing Fiat. Of course, it's still possible that decentralized stablecoin developers would comply with governments' demands by modifying the code. But the fact that they're open source, allows anyone to launch a "better version" that has not been "tainted" by governments' interests.
Nonetheless, we'll see how this plays along as people begin to lose trust in the world's banking system. The more people use stablecoins over regular Fiat, the worse it'll be for central banks' prominence within the mainstream world. With stablecoins you have the "best of both worlds" combining the power of Blockchain technology and the stability of Fiat. Eventually, governments will launch their own CBDCs which would serve the same purpose as a centralized stablecoin. Only decentralized ones will make the difference as it's outside the scope of third-parties. As long as there are people using and supporting the Blockchain industry, nothing should go wrong. Just my opinion