That is possible. But that will maybe happen in the future. And that will take a long time, because banks are important for the most people.
So it will be difficult to let that happen. And not that many people know how Bitcoin works so it will take time.
i doubt that it will be really difficult when people will start understanding that bitcoin is vital currency to have because of low fees
the replacement of banks will happen in something like 15 years in my opinion, as technologies are developing at a very rapid pace nowadays