Magstripe readers have been within the reach of any reasonably-clever fraudster for a long time. Attaching them to an iPhone and using audio modulation for the signal doesn't magically open the floodgates to card skimming and duplication.

This isn't even as big a threat as, say, making people acclimated to the idea of joining open wireless networks at coffee shops -- card skimming at least requires physical access to the card for a few seconds.