It's definitely something which will become more and more important, since there's really not much point in carrying a wallet just to have the information that could be easily available on the smartphones that most people possess.
What about safety issues? like from the backend maybe. Of course it is true that it is easier for people to do a cashless transaction and they do not even have to bring their wallets.
Hmm, i wonder how would these mobile point of sale evolve in the next generation.