It will be interesting to see if even Apple is able to change user habits. Visa and Mastercard might have signed on, but that's not important. Retailer support is the critical factor.
You clearly don't know the first thing about accepting credit and debit cards. Without the payment networks, NOTHING happens at point-of-sale.
Retail lives and dies by the Payment Card Industry standards and audits. Without Visa / MC / Discover / Amex, you are a cash-only business. Period.
I'm probably more ignorant that you realize, but that's beside the point. Visa/Mastercard support is necessary but not sufficient. The historical challenge for electronic but non-credit card systems has been placing readers at the point of sale locations. Without those readers, Apple Pay is useless. Someone has to pay for those readers. The stores don't want to do it unless they are convinced they can recover the cost.
If Apple can get either the stores or the banks to pass for the readers, then I will admit that Apple is an amazing magician. With the iPhone, Apple convinced AT&T et al. to subsidize the phones because the carriers were guaranteed to recover their investment through contracts with early termination fees. iPads don't come with such subsidies and are not as profitable for Apple. With Apple Pay, unless Apple swallows the cost of the readers, how will they convince the stores or banks for pay for the infrastructure without any guarantee of coming out ahead?