I don't think Satoshi built Bitcoin to take his banking friend's job. He wanted an alternative for all the deviousness of a centralized system. However, invention and innovation works as a lifestyle, nothing moves on faster than the Brain, look how everyone forgot the post office, yet it's here. Nothing ends anything, preferences makes the changes and it travels very fast across the world, billions of people can share one desire to use E-mail, and the few others would stick with the old method which they understand.

In other words, they're people who will never leave the bank for Bitcoin, even banks are still against the technology, not like there's a rapport between the two. But over the years to come, people won't rely so much on the banking system, which hits the goal of Satoshi.