It looks like it's compatible with the previous touch-card-to-reader-to-pay infrastructure that has been rolling out slowly. This is simply a way of having your phone emulate the card. So really, this technology builds onto an existing ecosystem, and since it integrates so easily (no upgrades from merchants) the main issue will be if they can get enough people to use it to make it profitable.

I'm having trouble finding the exact details. But that is the gist I'm getting.