Banks are not going anywhere even if bitcoin gets on the mainstream there will be many people who will prefer to use banks and save their money in it as they feel that banks are the most safest place to save their money which is actually true.
Well, it will not change even in the future. Banks are trusted by the people and it gives insurance to your money so people
are not worried anymore. However, it does not give you a good interest than holding bitcoins alone, but it's a person's choice on what make him comfortable.