I'm not sure what you are suggesting can change. You cannot completely bypass the big banks with just proximity payments. That's where the money is. Apple can help you move your money, from your bank account, to a merchant, into their bank account, but that's just Paypal level of functionality, nothing new.
Proximity non-card payments will change the situation for the debit/credit card operators, and possibly to a degree for Paypal-like services. Big banks are here to stay, and if they change something, it'll sooner be reasonably priced wire transfers to cut out the Paypal/cheque alternatives from hell.
You're thinking of a complete overall, whereas I am thinking a gradual disposition.
To some extent, the card is where the control is. PayPal knows this, which is why they came out with a debit and credit card.
If a proximity payment service emerged that could interact with the API inside a device, it is a matter of time before a "simple, affordable microtransaction" service/app comes about. From there, exponential growth due to the order of convenience and simplicity. Banks, meet your "Napster", as it were.
Imagine mint.com came out with a proximity payment system for all devices and used the existing mint.com system as your "Bank Account" overview. Simply amazing!
Proximity non-card payments will change the situation for the debit/credit card operators, and possibly to a degree for Paypal-like services. Big banks are here to stay, and if they change something, it'll sooner be reasonably priced wire transfers to cut out the Paypal/cheque alternatives from hell.