Bitcoin is something basic and should not be taken for more. What banks and other services do nowadays is something far more complex, including leveraging trust in a way or another. These kind of services can be built on top of BitCoin. Their business models won't be equivalent in all aspects with what we have now in the current system, but there is enough room and potential for such services to exist/run covering needs. It will be just a better system regarding the corruptible nature, because there won't be an central authority with whom to strike deals under the table and get empowered to "be a necessary evil".