Banks will change. It won't be as we know it today. But we will always have banks. I'm unaware of how bitcoin eliminates those functions. Imagine a world in which we only had bitcoin. There would still be a desire for some people to save and other people to borrow. Consequently something will emerge that provides those services. I suspect it will look a lot different than today's banks, but I'm guessing that most people will still call it a bank because it will provide all of the functions that they typically associated with a bank.