Yes, I think Bitcoin can make banks disappear, banks in general are used by people to transfer and receive money, store money (and gain interest by indirectly giving loans to other) and taking loans. Since the introduction of Bitcoin, we have seen some similar service that is going to give people loans in Bitcoin, and those who gives loan will gain interest. The flaw in this system is that there is no collateral (there is collateral at some loans, but majority of it doesn't have collateral instead the loan is taken and given by trust).
I think in the future there will be a dedicated feature in the blockchain that will hold the collateral of the lenders. So yes, Bitcoin may make banks disappear.
I doubt that a lot. What types of collateral will blockchain accept? There are lending sites like BTCJam and I had an interest in investing in sites that are like that. I read, though, that it's not a good idea to do so. People are just using fake IDs. In case someone defaulted on the loan, even though he posted his ID and a picture of him holding the ID, then what? You are not going to fly to another country or do all of the trouble just to chase a couple of bucks, would you? In this forum, there are collateral being accepted but most of the time, it's only the way of the other person to get rid of that collateral. It's like a way to sell that item. And so we ended up in the way loans are given by trust alone. The lender thinks that a hero member wouldn't risk his account getting negged for a couple of bucks but sometimes that is just not the case.
There are even trusted members here that destroyed their trust by getting a loan and not paying.