There will be a Google wallet app only if Apple allows it, which is unlikely. A more likely path is that Apple will partner with someone like Intuit (whose former CEO and current board chairman sits on Apple's board) and merge NFC in with Intuit's GoPay system. If Apple wants to do to the mobile payment industry what it did to the music industry it will partner with Intuit and offer merchants a "business ready" iPad 3 that will act as a POS terminal and hook in to something like an iOS version of quickbooks. Give away the hardware as a loss-leader for the payment service and cut a lot of middlemen out of the system.
Since Apple is already on the path to testing out iPad POS services in the Apple store they can refine the hardware/software and then roll out something that works well for both the user and the merchant.
