This is very cool but not a free lunch. The fees have to come from somewhere. How about no fees for chargebacks too?
So the product is only for businesses who meet all three of the following criteria:
1) small enough to not need over $21K per month of credit card charges
2) low enough chargeback risk that Square accepts/keeps them as a client
3) are currently paying more than $275 in fees per month with their current provider.
So bottom line this is a great marketing pitch but not really useful to the vast majority of companies in the real world. The odds of #2 and #3 both being true are basically nil for businesses small enough to meet #1.