If that happens then no amount of regulation is going to be enough, you will always find a person willing to accept bitcoin in exchange for products and services and when that happens there is going to be a significant number of people that are going to abandon fiat completely.
China is the perfect example of how anti regulations don't work to bannish crypto from the legal system. It made people switch to pure peer to peer trading which is the best way to avoid being subject to any government.
Funny is that China is now looking to step up their game by forcing popular payment apps to no longer process crypto related transactions. They're trying to use everything to stop crypto, but it's not working.
For the first time there isn't something governments can do to completely combat an emerging industry/technology, and people really start to notice that. Crypto is their way to more freedom, regardless of where they are.