Apple would prefer you to think that it's their own, exclusive, invention, but ApplePay is just one implementation of the industry-standard EMV Contactless payment protocol.
European customers have had contactless credit cards for over two years now, which, while not the same system (there's less intelligence in the cards), fill the same role as Apple's offering: speeding up low-value card purchases. These cards have the added advantage that you can use them when your phone battery is dead, or when you've lost your phone. There's a limit of around £20/€25/$30 on these transactions, but they're done with a simple tap of the credit card on the reader, much like a contactless subway/mass-transit card (although not as fast).
However, the USA is finally implementing EMV standards for credit card purchases, and it's very likely that merchants will go for terminals that do both Chip+PIN and Contactless. (In the USA, unlike many other countries, the merchant buys the card terminal outright - this is the reason for the delay in upgrading the country's payment infrastructure: the banks could not just swap out the rented terminals and make older systems obsolete like they did elsewhere).
ApplePay is never going to become a dominant player in a market where every credit-card will soon offer the same level of convenience: it'll just be a nice-to-have feature for iPhone users, not something that makes other buyers choose an iPhone (especially as both Android and Windows Phone will soon support contactless card payments too)