I don't think any crypto currency will totally replace banks to the point where they don't exist.
 I do however believe that their prominence and power will be drastically reduced in a similar fashion to that of record labels and the introduction of torrenting and youtube and the likes. prior to the internet era, record labels were practically a necessity, at least if you wanted to make it any ways big.

They had a monopoly on the music industry. you didn't succeed if they didn't want you to.
Now, they are still in existence, but they have little power or influence. crypto will do similar to the banks, clearing houses and all sorts of industries that we likely cant even fathom yet.