I maybe dreaming, but I imagine this. I'm browsing on my iPad, let's say I'm shopping Banana Republic. I hit checkout and it uses some Apple API where it knows I'm browsing on an iPad. Immediately it brings up thePay interface, I scan my fingerprint and I'm done. That's even easier than Amazon One Click, easier than Paypal!
On the subject ofPay on Android, something tells me that these patents are going to be licensed. That this method is backed by banks tells me that iPhone is just the first step for widespread adoption, but we'll have to wait and see.
I don't think that's too far-fetched at all. And I'm sure Google will plug Wallet into this system once it becomes more widespread. You can already use Google Wallet at NFC registers, so if it ever goes to the web, Wallet will get in there (hell, Softcard probably will too). I imagine one day you'll see websites with five or six payment options: CC, Paypal, Apple Pay, Wallet, Bitcoin, etc.