In the north east of England,
Nexus (they used the name since 1996 so not a Google reference) give their ticket inspectors NFC enabled Android phones in order to check passengers smartcard tickets.
Obviously as NFC in the iPhone is currently limited to Apple Pay it means they can't use iPhones for the same purpose, but in future perhaps it will be possible.
Anyway, there's nothing to stop an iPad with NFC capabilities being used both to accept Apple pay, contactless credit cards, Google Wallet and any other NFC cards the retailer accepts if Apple wants to allow that functionality.
Basically any NFC enabled card could then be accepted without any additional hardware and in some countries that would be sufficient for most customers. Areas where NFC penetration is low could add a chip and PIN or swipe reader in addition to this.