When bitcoin price hits 10,000$, Perhaps we will not use traditional currency (cash).
Untill that time, we will be using smart devices to pay everything with bitcoin.
I think no, the usage of bitcoin or fiat currency depends on the adoption of people on which currency they are accepting. Even if Bitcoin is $1M each if there are still a few merchants accepting bitcoin as payment, we are still forced to use currency as mode of payment. This is an indication that price of one currency is irrelevant whether the other currency will be worthless.