I think banks will not disappear.
They can change or can work with bitcoins.
but they will never disappear as fiat will never disappear too.
If fiat comes to the point that has no use already,
then thats the only time that banks can disappear.
But as i have said, its impossible.
Before thinking on the possibilities of bitcoin on making banks disappear when need to think what is the differences of the two. Bank and bitcoin is both a different denominator if we are going to compare the both side. Banks do have system where it needs fiat to move and to earn. While bitcoin is a way better currency like fiat so in other terms the common of the two is fiat. Their difference in all side but fiat make them somehow related to each other. I do not see bitcoin making bank disappear rather i can see that bank may accept bitcoin in the future for transaction like fiat system.