Cool. That's a great way to orange-pill merchants into appreciating Bitcoin - hopefully to the point of wanting to pass some or all of those savings onto their customers in order to attract more Bitcoin for themselves. (then, the question will be: does Square make it easy for merchants to choose to do so? e.g. option to automatically provide a 2% discount to the customer for purchases in Bitcoin).
Ultimately, a proper incentive structure should result in all participants benefiting by transacting in Bitcoin rather than fiat.