Banks would not disappear. Maybe the way banking works might become different, but even that is a remote possibility.
What you need to remember is that banking is big business. If bitcoin were to cause the banking industry problems, the banks would fight against bitcoin. And they would wage that war through government; By using legislation to keep bitcoin from causing problems to their industry. And government would happily play along.
yes banks will never disappear. but i think bank and wallet will work together. they will be really helpful for each other. and may be banks become more prfitalbe once they accept bitcoin.