I think the "how" part is the most interesting question here, both in terms of political justification (people who bought $100 of BTC on their coinbase app won't be very pleased) and practical enforcement. Of authors suggested measures, I think only the first would be necessary to result in a de-facto ban.
"Halt all wire transfers of dollars in and out of cryptocurrency exchanges.
Halt foreign entities trading in dollar cash-equivalent crypto assets.
Add Chinese and other foreign cryptocurrency exchanges hiding in tax-havens to sanctioned entities lists.
Regulate the sale of any existing cryptocurrency assets to US persons by classifying them as securities investment contracts moving forward."
"Halt all wire transfers of dollars in and out of cryptocurrency exchanges.
Halt foreign entities trading in dollar cash-equivalent crypto assets.
Add Chinese and other foreign cryptocurrency exchanges hiding in tax-havens to sanctioned entities lists.
Regulate the sale of any existing cryptocurrency assets to US persons by classifying them as securities investment contracts moving forward."