It shouldn't take much for Google Wallet and all other wallets to implement the same one-time-use credit card numbers as Apple Pay will use. Hopefully that intellectual property is owned by the payment processors, who have incentive to see the same process used across wallets, than by Apple, who might prefer lock-in. Apple needs to advocate a standard architecture that all parties, including their competitors, can use, while adding value by making the process simpler and most secure on their devices.
The biggest risk for mobile payments is fragmentation caused by the mobile carriers. We can't have AT&T, Verizon, and T-Mobile implementing different payment methods and blocking the use of any other payment methods. The carriers have blocked the use of different wallets in the past, for example AT&T initially did not allow Google Wallet to work on their phones.
Here is an example of where payment processing can go off the rails for consumers if companies like Google buy companies like Mastercard. We need separation between the back end and front end infrastructures to insure there is a standard back end that benefits all of us.