I don't think that the US will ban crypto, but for the sake of your argument, I think it will have a drastic impact on the market, we might see the price crashing because of this news. However, no country is bigger than bitcoin or the rest of the crypto. We might suffer a crash, but definitely it will grow again given sometime. We have seen how crypto's resiliency is, so no doubt that we can bounce back but it might take time, or until everything settles down after the ban.
The US is the most crypto friendly nations. They have strict laws for cryptocurrency but it does not mean they banned or will ban cryptocurrency. What we need actually is laws, regulations to prevent scam, ponzi schemes and bring cryptocurrency to mainstream.
Base on the fact, many crypto companies, exchanges, marketplaces, merchants are originated from the US, they will not suddenly ban cryptocurrency in the nation. It is impossible and unrealistic.
Big tech companies in the US already accepted or began to invest in cryptocurrency or expand their companies to blockchain. If the US won't ban Facebook, Twitter, Amazon, Microsoft, they won't ban cryptocurrency.