According to wold bank, there are around 2 billion people globally that are out of banking system due to different banking constraint. Bitcoin can be very useful tool to include all these bank less people into financial ecosystem. But bitcoin is not in a position to replace banks. Just like AirBnB coexist with hotels n uber with traditional taxis, bitcoin will coexist with banks.
First of all Bitcoin need to made it to main payment system, if it really wanna replace banks.