A lot of "bank hate" in this thread.
Of course, bitcoin is open source and available to everyone (including banks).
I strongly expect that some sort of audited, regulated, insured custody accounts will exist in the future. Nobody will be forced to use them, but many people will choose to use them. It will be very profitable for the institution that is holding the custody accounts, and many people who fear their own technical ability to secure their bitcoins will make use of such institutions.
Custody could be very cheap I believe (perhaps even as little as 50 USD per year). I personally think that the profitability would come from exchange/broker services. Banks usually charge a fee when (e.g.) you buy stock, or foreign currency.
Edit: payment services usually also charge a fee, to the merchant