In my opinion, BTC cannot kill banks because BTC shortages are
1. High transaction delivery fees
2. BTC does not have a fixed exchange rate like other currencies
3. If saving money in the form of BTC we are not certain of getting profits while banks have interest rates
Fiat is about to disappear.
There wont be such thing like a 'exchange rate' anymore because everything will be priced in Bitcoin.
Interest rates are going negative and people will have to take their money out of the banks and store it somewhere, and
the best option will be Bitcoin.