I kind of feel bad for Square Reader. But it’s totally useful where it eliminates the adapter. This is just the next step in technology, assuming the card holder has the built-in chip on the credit card.(Which most financial institutions have converted and/or are converting over to).
I don’t think that this means that Square Reader, SumUp and others will be pushed out of the market altogether. It could just add an extra convenient way of paying into these existing systems.
As others have mentioned, it would be interesting to learn Apple’s cut on transactions.