The problem here is not implementation and smartphone support, but adoption by merchants. There're still shops that do not accept regular credit cards out there, and this is a new type of technology that they must somehow accomodate. So, yeah, 2-5 years to iron out the kinks, but about 10 to make it a real mainstream thing. And god help us if there will be competing standards.

Speaking of competing standards. I have this Visa "blink" card from Chase. The supermarket where I shop, has terminals that accept "blink". Guess how often can I use my card there? The thing works maybe once in ten times I actually am trying to pass my card over the sensor. It's just easier to swipe it in the first place.