My sense is that a key acquirer is pondering the incremental value of Apple Pay. Apple Pay like Google Wallet, SoftCard and contactless cards is not by itself going to ignite the use of mobile wallets.. Apple Pay, a well implemented consumer experience, has not created merchant benefit. The consumer may save a second or two, but as Karen suggests if it is simply in parallel with the bagging of the groceries, what benefit does the merchant see?

Increase the size of the basket - cards do that. Increase frequency - coupons and service do that. Increase loyalty - being able to tap and pay does not do that. The merchant is looking for revenue and tapping instead of dipping / swiping does not increase revenue.
We should once again thank Apple for creating buzz. We still await the compelling shopping experience to ignite mobile commerce.