nope, I don't think so. Both of them are different currencies, a currency won't fall down that easily
bitcoins and dollars are different currencies, I also agree with you, bitcoin is a digital currency that for now exists only in digital systems whereas dollars are the currency of a country, and it is very unlikely that a country's currency is replaced with another currency
Bitcoin is not a legal currency and that word currency is only by definition in the crypto world.
USD is a legal currency and created by the government of the US and it's widely accepted all over the world without a risk, so people would choose
USD because they will only use it to transact, not to invest.