The US government didn't "ban" the Tornado.Cash smart contract because that would be practically impossible to achieve (the ETH blockchain is decentralized, after all). What they did was sanction the mixer, causing centralized service providers to shut down its GitHub repository and frontend interface. Without the source code and a web GUI where you could easily access Tornado.Cash, adoption would be virtually non-existent. Only geeks and crypto veterans would still be able to use the mixer by interacting with smart contracts directly. What the US government did is a precedent of what's coming in the future.

I'm afraid the US and other countries will exert more pressure against mixers and privacy coins, as they move an inch closer to launching their own Central Bank Digital Currencies (CBDCs). After all, governments wouldn't want people using decentralized tech that would minimize their authority/sovereignty. It's possible privacy coins will stop being traded at centralized exchanges, while mixers will be outlawed for good. You'd still be able to use such services because of their decentralized and censorship-resistant design. But it wouldn't be worth the risk as you could face jail time or be required to pay a fine. It's a dark future ahead for crypto/Blockchain tech, so we should be prepared for the worst. Just my thoughts