My idea is that a bank or an establishment that totally focuses with banking service but the currency will be in cryptocurrencies, mainly with bitcoin and few altcoins.
Bank for cryptocurrency will ruin the basic principle of being your own bank without the need to trust any 3rd party. However it might serve good purpose due to some people being used to ordinary banking which means that they are used to ask somebody for every trouble they have. They don't want to think for themselves. But banking with crypto should be secure, very secure. There are some banks trying to be made such as crypterium and bankera but we have yet to see what they can do.
I think he is suggesting a bank service that if you deposit your cryptocurrency you will get an interest annually by simply depositing it regardless of the current price and value of bitcoin just like the flat currency. Maybe its too risky to do this but its worth it to to give a try because the market is still young and we can do many things like loan services that could make our bitcoin grow specially if you don't have the money to start yet.